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Fu L, Gu C, Mochizuki K, Xiong J, Miao W, Wang G. The genome-wide meiotic recombination landscape in ciliates and its implications for crossover regulation and genome evolution. J Genet Genomics 2024; 51:302-312. [PMID: 37797835 DOI: 10.1016/j.jgg.2023.09.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Revised: 09/26/2023] [Accepted: 09/27/2023] [Indexed: 10/07/2023]
Abstract
Meiotic recombination is essential for sexual reproduction and its regulation has been extensively studied in many taxa. However, genome-wide recombination landscape has not been reported in ciliates and it remains unknown how it is affected by the unique features of ciliates: the synaptonemal complex (SC)-independent meiosis and the nuclear dimorphism. Here, we show the recombination landscape in the model ciliate Tetrahymena thermophila by analyzing single-nucleotide polymorphism datasets from 38 hybrid progeny. We detect 1021 crossover (CO) events (35.8 per meiosis), corresponding to an overall CO rate of 9.9 cM/Mb. However, gene conversion by non-crossover is rare (1.03 per meiosis) and not biased towards G or C alleles. Consistent with the reported roles of SC in CO interference, we find no obvious sign of CO interference. CO tends to occur within germ-soma common genomic regions and many of the 44 identified CO hotspots localize at the centromeric or subtelomeric regions. Gene ontology analyses show that CO hotspots are strongly associated with genes responding to environmental changes. We discuss these results with respect to how nuclear dimorphism has potentially driven the formation of the observed recombination landscape to facilitate environmental adaptation and the sharing of machinery among meiotic and somatic recombination.
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Affiliation(s)
- Lu Fu
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chen Gu
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kazufumi Mochizuki
- Institute of Human Genetics (IGH), CNRS, University of Montpellier, 34396 Montpellier, France
| | - Jie Xiong
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China; Key Laboratory of Breeding Biotechnology and Sustainable Aquaculture, Chinese Academy of Sciences, Wuhan, Hubei 430072, China
| | - Wei Miao
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China; Key Laboratory of Lake and Watershed Science for Water Security, Chinese Academy of Sciences, Nanjing, Jiangsu 210008, China.
| | - Guangying Wang
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China.
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Ouaja M, Bahri BA, Ferjaoui S, Medini M, Sripada UM, Hamza S. Unlocking the story of resistance to Zymoseptoria tritici in Tunisian old durum wheat germplasm based on population structure analysis. BMC Genomics 2023; 24:328. [PMID: 37322410 DOI: 10.1186/s12864-023-09395-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 05/20/2023] [Indexed: 06/17/2023] Open
Abstract
BACKGROUND Septoria tritici blotch (STB) remains a significant obstacle to durum wheat cultivation on a global scale. This disease remains a challenge for farmers, researchers, and breeders, who are collectively dedicated to reduce its damage and improve wheat resistance. Tunisian durum wheat landraces have been recognized as valuable genetic ressources that exhibit resistance to biotic and abiotic stresses and therefore play a crucial role in breeding program aimed at creating new wheat varieties resistant to fungal diseases as STB, as well as adapted to climate change constraints. RESULTS A total of 366 local durum wheat accessions were assessed for resistance to two virulent Tunisian isolates of Zymoseptoria tritici Tun06 and TM220 under field conditions. Population structure analysis of the durum wheat accessions, performed with 286 polymorphic SNPs (PIC > 0.3) covering the entire genome, identified three genetic subpopulations (GS1, GS2 and GS3) with 22% of admixed genotypes. Interestingly, all of the resistant genotypes were among GS2 or admixed with GS2. CONCLUSIONS This study revealed the population structure and the genetic distribution of the resistance to Z. tritici in the Tunisian durum wheat landraces. Accessions grouping pattern reflected the geographical origins of the landraces. We suggested that GS2 accessions were mostly derived from eastern Mediterranean populations, unlike GS1 and GS3 that originated from the west. Resistant GS2 accessions belonged to landraces Taganrog, Sbei glabre, Richi, Mekki, Badri, Jneh Khotifa and Azizi. Furthermore, we suggested that admixture contributed to transmit STB resistance from GS2 resistant landraces to initially susceptible landraces such as Mahmoudi (GS1), but also resulted in the loss of resistance in the case of GS2 susceptible Azizi and Jneh Khotifa accessions.
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Affiliation(s)
- Maroua Ouaja
- Department of agronomy and plant biotechnology, Laboratory of genetics and cereal breeding (LR14AGR01), The National Agronomic Institute of Tunisia (INAT), University of Carthage, 43 Avenue Charles-Nicolle, Tunis, 1082, Tunisia
| | - Bochra A Bahri
- Department of agronomy and plant biotechnology, Laboratory of genetics and cereal breeding (LR14AGR01), The National Agronomic Institute of Tunisia (INAT), University of Carthage, 43 Avenue Charles-Nicolle, Tunis, 1082, Tunisia
- Department of Plant Pathology, Institute of Plant Breeding, Genetics and Genomics, University of Georgia, Griffin, GA, 30223, USA
| | - Sahbi Ferjaoui
- Field Crops Laboratory, Regional Field Crops Research Center of Beja (CRRGC), P.O. Box 350, Beja, 9000, Tunisia
| | - Maher Medini
- Banque Nationale des Gènes (BNG), Boulevard du Leader Yasser Arafat Z. I Charguia 1, Tunis, 1080, Tunisie
| | - Udupa M Sripada
- International Center for Agricultural Research in the Dry Areas (ICARDA), Avenue Hafiane Cherkaoui, Rabat, Marocco
| | - Sonia Hamza
- Department of agronomy and plant biotechnology, Laboratory of genetics and cereal breeding (LR14AGR01), The National Agronomic Institute of Tunisia (INAT), University of Carthage, 43 Avenue Charles-Nicolle, Tunis, 1082, Tunisia.
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3
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Ortiz V, Chang HX, Sang H, Jacobs J, Malvick DK, Baird R, Mathew FM, Estévez de Jensen C, Wise KA, Mosquera GM, Chilvers MI. Population genomic analysis reveals geographic structure and climatic diversification for Macrophomina phaseolina isolated from soybean and dry bean across the United States, Puerto Rico, and Colombia. Front Genet 2023; 14:1103969. [PMID: 37351341 PMCID: PMC10282554 DOI: 10.3389/fgene.2023.1103969] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 04/20/2023] [Indexed: 06/24/2023] Open
Abstract
Macrophomina phaseolina causes charcoal rot, which can significantly reduce yield and seed quality of soybean and dry bean resulting from primarily environmental stressors. Although charcoal rot has been recognized as a warm climate-driven disease of increasing concern under global climate change, knowledge regarding population genetics and climatic variables contributing to the genetic diversity of M. phaseolina is limited. This study conducted genome sequencing for 95 M. phaseolina isolates from soybean and dry bean across the continental United States, Puerto Rico, and Colombia. Inference on the population structure using 76,981 single nucleotide polymorphisms (SNPs) revealed that the isolates exhibited a discrete genetic clustering at the continental level and a continuous genetic differentiation regionally. A majority of isolates from the United States (96%) grouped in a clade with a predominantly clonal genetic structure, while 88% of Puerto Rican and Colombian isolates from dry bean were assigned to a separate clade with higher genetic diversity. A redundancy analysis (RDA) was used to estimate the contributions of climate and spatial structure to genomic variation (11,421 unlinked SNPs). Climate significantly contributed to genomic variation at a continental level with temperature seasonality explaining the most variation while precipitation of warmest quarter explaining the most when spatial structure was accounted for. The loci significantly associated with multivariate climate were found closely to the genes related to fungal stress responses, including transmembrane transport, glycoside hydrolase activity and a heat-shock protein, which may mediate climatic adaptation for M. phaseolina. On the contrary, limited genome-wide differentiation among populations by hosts was observed. These findings highlight the importance of population genetics and identify candidate genes of M. phaseolina that can be used to elucidate the molecular mechanisms that underly climatic adaptation to the changing climate.
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Affiliation(s)
- Viviana Ortiz
- Department of Plant, Soil and Microbial Sciences, College of Agriculture and Natural Resources, Michigan State University, East Lansing, MI, United States
- Ecology, Evolution and Behavior Program, Michigan State University, East Lansing, MI, United States
| | - Hao-Xun Chang
- Department of Plant Pathology and Microbiology, National Taiwan University, Taipei, Taiwan
| | - Hyunkyu Sang
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, Republic of Korea
| | - Janette Jacobs
- Department of Plant, Soil and Microbial Sciences, College of Agriculture and Natural Resources, Michigan State University, East Lansing, MI, United States
| | - Dean K. Malvick
- Department of Plant Pathology, University of Minnesota, St. Paul, MN, United States
| | - Richard Baird
- BCH-EPP Department, Mississippi State University, Mississippi State, MS, United States
| | - Febina M. Mathew
- Department of Plant Pathology, North Dakota State University, Fargo, ND, United States
| | | | - Kiersten A. Wise
- Department of Plant Pathology, College of Agriculture, Food and Environment, University of Kentucky, Princeton, KY, United States
| | - Gloria M. Mosquera
- Plant Pathology, Crops for Nutrition and Health, International Center for Tropical Agriculture (CIAT), The Americas Hub, Palmira, Colombia
| | - Martin I. Chilvers
- Department of Plant, Soil and Microbial Sciences, College of Agriculture and Natural Resources, Michigan State University, East Lansing, MI, United States
- Ecology, Evolution and Behavior Program, Michigan State University, East Lansing, MI, United States
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4
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Meile L, Garrido-Arandia M, Bernasconi Z, Peter J, Schneller A, Bernasconi A, Alassimone J, McDonald BA, Sánchez-Vallet A. Natural variation in Avr3D1 from Zymoseptoria sp. contributes to quantitative gene-for-gene resistance and to host specificity. THE NEW PHYTOLOGIST 2023; 238:1562-1577. [PMID: 36529883 DOI: 10.1111/nph.18690] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 12/06/2022] [Indexed: 06/17/2023]
Abstract
Successful host colonization by plant pathogens requires the circumvention of host defense responses, frequently through sequence modifications in secreted pathogen proteins known as avirulence factors (Avrs). Although Avr sequences are often polymorphic, the contribution of these polymorphisms to virulence diversity in natural pathogen populations remains largely unexplored. We used molecular genetic tools to determine how natural sequence polymorphisms of the avirulence factor Avr3D1 in the wheat pathogen Zymoseptoria tritici contributed to adaptive changes in virulence. We showed that there is a continuous distribution in the magnitude of resistance triggered by different Avr3D1 isoforms and demonstrated that natural variation in an Avr gene can lead to a quantitative resistance phenotype. We further showed that homologues of Avr3D1 in two nonpathogenic sister species of Z. tritici are recognized by some wheat cultivars, suggesting that Avr-R gene-for-gene interactions can contribute to nonhost resistance. We suggest that the mechanisms underlying host range, qualitative resistance, and quantitative resistance are not exclusive.
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Affiliation(s)
- Lukas Meile
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), 28223, Pozuelo de Alarcón, Madrid, Spain
| | - María Garrido-Arandia
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), 28223, Pozuelo de Alarcón, Madrid, Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid (UPM), 28040, Madrid, Spain
| | - Zoe Bernasconi
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
| | - Jules Peter
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
| | - Alissa Schneller
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
| | - Alessio Bernasconi
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
| | - Julien Alassimone
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
| | - Bruce A McDonald
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
| | - Andrea Sánchez-Vallet
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Universitätstrasse 2, Zurich, 8092, Switzerland
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), 28223, Pozuelo de Alarcón, Madrid, Spain
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5
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Lovelace AH, Dorhmi S, Hulin MT, Li Y, Mansfield JW, Ma W. Effector Identification in Plant Pathogens. PHYTOPATHOLOGY 2023; 113:637-650. [PMID: 37126080 DOI: 10.1094/phyto-09-22-0337-kd] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Effectors play a central role in determining the outcome of plant-pathogen interactions. As key virulence proteins, effectors are collectively indispensable for disease development. By understanding the virulence mechanisms of effectors, fundamental knowledge of microbial pathogenesis and disease resistance have been revealed. Effectors are also considered double-edged swords because some of them activate immunity in disease resistant plants after being recognized by specific immune receptors, which evolved to monitor pathogen presence or activity. Characterization of effector recognition by their cognate immune receptors and the downstream immune signaling pathways is instrumental in implementing resistance. Over the past decades, substantial research effort has focused on effector biology, especially concerning their interactions with virulence targets or immune receptors in plant cells. A foundation of this research is robust identification of the effector repertoire from a given pathogen, which depends heavily on bioinformatic prediction. In this review, we summarize methodologies that have been used for effector mining in various microbial pathogens which use different effector delivery mechanisms. We also discuss current limitations and provide perspectives on how recently developed analytic tools and technologies may facilitate effector identification and hence generation of a more complete vision of host-pathogen interactions. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
| | - Sara Dorhmi
- The Sainsbury Laboratory, Norwich, NR4 7UH, U.K
- Department of Microbiology and Plant Pathology, University of California Riverside, CA 92521, U.S.A
| | | | - Yufei Li
- The Sainsbury Laboratory, Norwich, NR4 7UH, U.K
| | - John W Mansfield
- Faculty of Natural Sciences, Imperial College London, London, SW7 2BX, U.K
| | - Wenbo Ma
- The Sainsbury Laboratory, Norwich, NR4 7UH, U.K
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6
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Moutinho AF, Eyre-Walker A, Dutheil JY. Strong evidence for the adaptive walk model of gene evolution in Drosophila and Arabidopsis. PLoS Biol 2022; 20:e3001775. [PMID: 36099311 PMCID: PMC9470001 DOI: 10.1371/journal.pbio.3001775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 08/01/2022] [Indexed: 11/19/2022] Open
Abstract
Understanding the dynamics of species adaptation to their environments has long been a central focus of the study of evolution. Theories of adaptation propose that populations evolve by “walking” in a fitness landscape. This “adaptive walk” is characterised by a pattern of diminishing returns, where populations further away from their fitness optimum take larger steps than those closer to their optimal conditions. Hence, we expect young genes to evolve faster and experience mutations with stronger fitness effects than older genes because they are further away from their fitness optimum. Testing this hypothesis, however, constitutes an arduous task. Young genes are small, encode proteins with a higher degree of intrinsic disorder, are expressed at lower levels, and are involved in species-specific adaptations. Since all these factors lead to increased protein evolutionary rates, they could be masking the effect of gene age. While controlling for these factors, we used population genomic data sets of Arabidopsis and Drosophila and estimated the rate of adaptive substitutions across genes from different phylostrata. We found that a gene’s evolutionary age significantly impacts the molecular rate of adaptation. Moreover, we observed that substitutions in young genes tend to have larger physicochemical effects. Our study, therefore, provides strong evidence that molecular evolution follows an adaptive walk model across a large evolutionary timescale. This study uses population genomic datasets from Arabidopsis and Drosophila to show that young genes adapt faster and are subject to mutations of larger fitness effects, providing strong evidence that molecular evolution follows an adaptive walk model across a large evolutionary timescale.
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Affiliation(s)
- Ana Filipa Moutinho
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Biology, Plön, Germany
- School of Life Sciences, University of Sussex, Brighton, United Kingdom
- * E-mail:
| | - Adam Eyre-Walker
- School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Julien Y. Dutheil
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Biology, Plön, Germany
- Unité Mixte de Recherche 5554 Institut des Sciences de l’Evolution, CNRS, IRD, EPHE, Université de Montpellier, Montpellier, France
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7
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Thierry M, Charriat F, Milazzo J, Adreit H, Ravel S, Cros-Arteil S, borron S, Sella V, Kroj T, Ioos R, Fournier E, Tharreau D, Gladieux P. Maintenance of divergent lineages of the Rice Blast Fungus Pyricularia oryzae through niche separation, loss of sex and post-mating genetic incompatibilities. PLoS Pathog 2022; 18:e1010687. [PMID: 35877779 PMCID: PMC9352207 DOI: 10.1371/journal.ppat.1010687] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 08/04/2022] [Accepted: 06/17/2022] [Indexed: 11/18/2022] Open
Abstract
Many species of fungal plant pathogens coexist as multiple lineages on the same host, but the factors underlying the origin and maintenance of population structure remain largely unknown. The rice blast fungus Pyricularia oryzae is a widespread model plant pathogen displaying population subdivision. However, most studies of natural variation in P. oryzae have been limited in genomic or geographic resolution, and host adaptation is the only factor that has been investigated extensively as a contributor to population subdivision. In an effort to complement previous studies, we analyzed genetic and phenotypic diversity in isolates of the rice blast fungus covering a broad geographical range. Using single-nucleotide polymorphism genotyping data for 886 isolates sampled from 152 sites in 51 countries, we showed that population subdivision of P. oryzae in one recombining and three clonal lineages with broad distributions persisted with deeper sampling. We also extended previous findings by showing further population subdivision of the recombining lineage into one international and three Asian clusters, and by providing evidence that the three clonal lineages of P. oryzae were found in areas with different prevailing environmental conditions, indicating niche separation. Pathogenicity tests and bioinformatic analyses using an extended set of isolates and rice varieties indicated that partial specialization to rice subgroups contributed to niche separation between lineages, and differences in repertoires of putative virulence effectors were consistent with differences in host range. Experimental crosses revealed that female sterility and early post-mating genetic incompatibilities acted as strong additional barriers to gene flow between clonal lineages. Our results demonstrate that the spread of a fungal pathogen across heterogeneous habitats and divergent populations of a crop species can lead to niche separation and reproductive isolation between distinct, widely distributed, lineages.
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Affiliation(s)
- Maud Thierry
- PHIM Plant Health Institute, Univ Montpellier, INRAE, CIRAD, Institut Agro, IRD, Montpellier, France
- CIRAD, UMR PHIM, Montpellier, France
- ANSES Plant Health Laboratory, Mycology Unit, Malzéville, France
| | - Florian Charriat
- PHIM Plant Health Institute, Univ Montpellier, INRAE, CIRAD, Institut Agro, IRD, Montpellier, France
| | - Joëlle Milazzo
- PHIM Plant Health Institute, Univ Montpellier, INRAE, CIRAD, Institut Agro, IRD, Montpellier, France
- CIRAD, UMR PHIM, Montpellier, France
| | - Henri Adreit
- PHIM Plant Health Institute, Univ Montpellier, INRAE, CIRAD, Institut Agro, IRD, Montpellier, France
- CIRAD, UMR PHIM, Montpellier, France
| | - Sébastien Ravel
- PHIM Plant Health Institute, Univ Montpellier, INRAE, CIRAD, Institut Agro, IRD, Montpellier, France
- CIRAD, UMR PHIM, Montpellier, France
| | - Sandrine Cros-Arteil
- PHIM Plant Health Institute, Univ Montpellier, INRAE, CIRAD, Institut Agro, IRD, Montpellier, France
| | - Sonia borron
- PHIM Plant Health Institute, Univ Montpellier, INRAE, CIRAD, Institut Agro, IRD, Montpellier, France
| | - Violaine Sella
- ANSES Plant Health Laboratory, Mycology Unit, Malzéville, France
| | - Thomas Kroj
- PHIM Plant Health Institute, Univ Montpellier, INRAE, CIRAD, Institut Agro, IRD, Montpellier, France
| | - Renaud Ioos
- ANSES Plant Health Laboratory, Mycology Unit, Malzéville, France
| | - Elisabeth Fournier
- PHIM Plant Health Institute, Univ Montpellier, INRAE, CIRAD, Institut Agro, IRD, Montpellier, France
| | - Didier Tharreau
- PHIM Plant Health Institute, Univ Montpellier, INRAE, CIRAD, Institut Agro, IRD, Montpellier, France
- CIRAD, UMR PHIM, Montpellier, France
- * E-mail: (DT); (PG)
| | - Pierre Gladieux
- PHIM Plant Health Institute, Univ Montpellier, INRAE, CIRAD, Institut Agro, IRD, Montpellier, France
- * E-mail: (DT); (PG)
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8
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Förster C, Handrick V, Ding Y, Nakamura Y, Paetz C, Schneider B, Castro-Falcón G, Hughes CC, Luck K, Poosapati S, Kunert G, Huffaker A, Gershenzon J, Schmelz EA, Köllner TG. Biosynthesis and antifungal activity of fungus-induced O-methylated flavonoids in maize. PLANT PHYSIOLOGY 2022; 188:167-190. [PMID: 34718797 PMCID: PMC8774720 DOI: 10.1093/plphys/kiab496] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 09/30/2021] [Indexed: 05/05/2023]
Abstract
Fungal infection of grasses, including rice (Oryza sativa), sorghum (Sorghum bicolor), and barley (Hordeum vulgare), induces the formation and accumulation of flavonoid phytoalexins. In maize (Zea mays), however, investigators have emphasized benzoxazinoid and terpenoid phytoalexins, and comparatively little is known about flavonoid induction in response to pathogens. Here, we examined fungus-elicited flavonoid metabolism in maize and identified key biosynthetic enzymes involved in the formation of O-methylflavonoids. The predominant end products were identified as two tautomers of a 2-hydroxynaringenin-derived compound termed xilonenin, which significantly inhibited the growth of two maize pathogens, Fusarium graminearum and Fusarium verticillioides. Among the biosynthetic enzymes identified were two O-methyltransferases (OMTs), flavonoid OMT 2 (FOMT2), and FOMT4, which demonstrated distinct regiospecificity on a broad spectrum of flavonoid classes. In addition, a cytochrome P450 monooxygenase (CYP) in the CYP93G subfamily was found to serve as a flavanone 2-hydroxylase providing the substrate for FOMT2-catalyzed formation of xilonenin. In summary, maize produces a diverse blend of O-methylflavonoids with antifungal activity upon attack by a broad range of fungi.
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Affiliation(s)
- Christiane Förster
- Department of Biochemistry, Max Planck Institute for Chemical Ecology, Jena D-07745, Germany
| | - Vinzenz Handrick
- Department of Biochemistry, Max Planck Institute for Chemical Ecology, Jena D-07745, Germany
| | - Yezhang Ding
- Section of Cell and Developmental Biology, University of California, San Diego, California 92093-0380, USA
| | - Yoko Nakamura
- Research Group Biosynthesis/NMR, Max Planck Institute for Chemical Ecology, Jena D-07745, Germany
| | - Christian Paetz
- Research Group Biosynthesis/NMR, Max Planck Institute for Chemical Ecology, Jena D-07745, Germany
| | - Bernd Schneider
- Research Group Biosynthesis/NMR, Max Planck Institute for Chemical Ecology, Jena D-07745, Germany
| | - Gabriel Castro-Falcón
- Scripps Institution of Oceanography, University of California, San Diego, California 92093, USA
| | - Chambers C Hughes
- Scripps Institution of Oceanography, University of California, San Diego, California 92093, USA
| | - Katrin Luck
- Department of Biochemistry, Max Planck Institute for Chemical Ecology, Jena D-07745, Germany
| | - Sowmya Poosapati
- Section of Cell and Developmental Biology, University of California, San Diego, California 92093-0380, USA
| | - Grit Kunert
- Department of Biochemistry, Max Planck Institute for Chemical Ecology, Jena D-07745, Germany
| | - Alisa Huffaker
- Section of Cell and Developmental Biology, University of California, San Diego, California 92093-0380, USA
| | - Jonathan Gershenzon
- Department of Biochemistry, Max Planck Institute for Chemical Ecology, Jena D-07745, Germany
| | - Eric A Schmelz
- Section of Cell and Developmental Biology, University of California, San Diego, California 92093-0380, USA
| | - Tobias G Köllner
- Department of Biochemistry, Max Planck Institute for Chemical Ecology, Jena D-07745, Germany
- Author for communication:
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9
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Oggenfuss U, Badet T, Wicker T, Hartmann FE, Singh NK, Abraham L, Karisto P, Vonlanthen T, Mundt C, McDonald BA, Croll D. A population-level invasion by transposable elements triggers genome expansion in a fungal pathogen. eLife 2021; 10:e69249. [PMID: 34528512 PMCID: PMC8445621 DOI: 10.7554/elife.69249] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 08/28/2021] [Indexed: 12/16/2022] Open
Abstract
Genome evolution is driven by the activity of transposable elements (TEs). The spread of TEs can have deleterious effects including the destabilization of genome integrity and expansions. However, the precise triggers of genome expansions remain poorly understood because genome size evolution is typically investigated only among deeply divergent lineages. Here, we use a large population genomics dataset of 284 individuals from populations across the globe of Zymoseptoria tritici, a major fungal wheat pathogen. We built a robust map of genome-wide TE insertions and deletions to track a total of 2456 polymorphic loci within the species. We show that purifying selection substantially depressed TE frequencies in most populations, but some rare TEs have recently risen in frequency and likely confer benefits. We found that specific TE families have undergone a substantial genome-wide expansion from the pathogen's center of origin to more recently founded populations. The most dramatic increase in TE insertions occurred between a pair of North American populations collected in the same field at an interval of 25 years. We find that both genome-wide counts of TE insertions and genome size have increased with colonization bottlenecks. Hence, the demographic history likely played a major role in shaping genome evolution within the species. We show that both the activation of specific TEs and relaxed purifying selection underpin this incipient expansion of the genome. Our study establishes a model to recapitulate TE-driven genome evolution over deeper evolutionary timescales.
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Affiliation(s)
- Ursula Oggenfuss
- Laboratory of Evolutionary Genetics, Institute of Biology, University of NeuchâtelNeuchatelSwitzerland
| | - Thomas Badet
- Laboratory of Evolutionary Genetics, Institute of Biology, University of NeuchâtelNeuchatelSwitzerland
| | - Thomas Wicker
- Institute for Plant and Microbial Biology, University of ZurichZurichSwitzerland
| | - Fanny E Hartmann
- Ecologie Systématique Evolution, Bâtiment 360, Univ. Paris-Sud, AgroParisTech, CNRS, Université Paris-SaclayOrsayFrance
- Plant Pathology, Institute of Integrative Biology, ETH ZurichZurichSwitzerland
| | - Nikhil Kumar Singh
- Laboratory of Evolutionary Genetics, Institute of Biology, University of NeuchâtelNeuchatelSwitzerland
| | - Leen Abraham
- Laboratory of Evolutionary Genetics, Institute of Biology, University of NeuchâtelNeuchatelSwitzerland
| | - Petteri Karisto
- Plant Pathology, Institute of Integrative Biology, ETH ZurichZurichSwitzerland
| | - Tiziana Vonlanthen
- Plant Pathology, Institute of Integrative Biology, ETH ZurichZurichSwitzerland
| | - Christopher Mundt
- Department of Botany and Plant Pathology, Oregon State UniversityCorvallisUnited States
| | - Bruce A McDonald
- Plant Pathology, Institute of Integrative Biology, ETH ZurichZurichSwitzerland
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of NeuchâtelNeuchatelSwitzerland
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10
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Odjo T, Diagne D, Adreit H, Milazzo J, Raveloson H, Andriantsimialona D, Kassankogno AI, Ravel S, Gumedzoé YMD, Ouedraogo I, Koita O, Silué D, Tharreau D. Structure of African Populations of Pyricularia oryzae from Rice. PHYTOPATHOLOGY 2021; 111:1428-1437. [PMID: 33386066 DOI: 10.1094/phyto-05-20-0186-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Rice blast, caused by the filamentous ascomycete Pyricularia oryzae, is one of the most devastating diseases of rice. Four genetic clusters were previously identified, and three have a large geographic distribution. Asia is the center of diversity and the origin of most migrations to other continents, and sexual reproduction persisted only in the South China-Laos-North Thailand region, which was identified as the putative center of origin of all P. oryzae populations on rice. Despite the importance of rice blast disease, little is known about the diversity and the population structure of the pathogen in Africa (including Madagascar). The present study was intended to describe the structure of African populations of P. oryzae and identify the relationship between African and worldwide genetic clusters. A set of 2,057 strains (937 African and 1,120 Madagascan strains) were genotyped with 12 simple sequence repeat markers to assess the diversity and the population structure of P. oryzae. Four genetic clusters were identified in Africa and Madagascar. All four clusters previously identified are present in Africa. Populations from West Africa, East Africa, and Madagascar are highly differentiated. The geographic structure is consistent with limited dispersion and with some migration events between neighboring countries. The two mating types are present in Africa with a dominance of Mat1.2, but no female-fertile strain was detected, supporting the absence of sexual reproduction on this continent. This study showed an unsuspected high level of genetic diversity of P. oryzae in Africa and suggested several independent introductions.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Théophile Odjo
- Faculté des Sciences Agronomiques de l'Université d'Abomey-Calavi, 01 BP526 Cotonou, Bénin
| | - Diariatou Diagne
- Laboratoire de Biologie Moléculaire Appliquée, Université des Sciences, des Techniques et des Technologies de Bamako, Faculté des Sciences et Techniques, BP E 3206 Bamako, Mali
| | - Henri Adreit
- UMR BGPI, CIRAD, TA A54/K, 34398 Montpellier, France. BGPI, Université de Montpellier, CIRAD, INRA, Montpellier SupAgro, Montpellier, France
| | - Joëlle Milazzo
- UMR BGPI, CIRAD, TA A54/K, 34398 Montpellier, France. BGPI, Université de Montpellier, CIRAD, INRA, Montpellier SupAgro, Montpellier, France
| | | | - Dodelys Andriantsimialona
- Centre Régional de Recherches Fofifa, 110 BP230 Antsirabe, Madagascar
- South Green Bioinformatics Platform, Bioversity, CIRAD, INRA, IRD, 34398 Montpellier, France
| | | | - Sébastien Ravel
- UMR BGPI, CIRAD, TA A54/K, 34398 Montpellier, France. BGPI, Université de Montpellier, CIRAD, INRA, Montpellier SupAgro, Montpellier, France
| | | | - Ibrahima Ouedraogo
- Institut de l'Environnement et Recherches Agricoles, BP 910 Bobo-Dioulasso, Burkina Faso
| | - Ousmane Koita
- Laboratoire de Biologie Moléculaire Appliquée, Université des Sciences, des Techniques et des Technologies de Bamako, Faculté des Sciences et Techniques, BP E 3206 Bamako, Mali
| | | | - Didier Tharreau
- UMR BGPI, CIRAD, TA A54/K, 34398 Montpellier, France. BGPI, Université de Montpellier, CIRAD, INRA, Montpellier SupAgro, Montpellier, France
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11
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Derbyshire MC, Harper LA, Lopez-Ruiz FJ. Positive Selection of Transcription Factors Is a Prominent Feature of the Evolution of a Plant Pathogenic Genus Originating in the Miocene. Genome Biol Evol 2021; 13:6325025. [PMID: 34289036 PMCID: PMC8379374 DOI: 10.1093/gbe/evab167] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/12/2021] [Indexed: 01/18/2023] Open
Abstract
Tests based on the dN/dS statistic are used to identify positive selection of nonsynonymous polymorphisms. Using these tests on alignments of all orthologs from related species can provide insights into which gene categories have been most frequently positively selected. However, longer alignments have more power to detect positive selection, creating a detection bias that could create misleading results from functional enrichment tests. Most studies of positive selection in plant pathogens focus on genes with specific virulence functions, with little emphasis on broader molecular processes. Furthermore, no studies in plant pathogens have accounted for detection bias due to alignment length when performing functional enrichment tests. To address these research gaps, we analyze 12 genomes of the phytopathogenic fungal genus Botrytis, including two sequenced in this study. To establish a temporal context, we estimated fossil-calibrated divergence times for the genus. We find that Botrytis likely originated 16–18 Ma in the Miocene and underwent continuous radiation ending in the Pliocene. An untargeted scan of Botrytis single-copy orthologs for positive selection with three different statistical tests uncovered evidence for positive selection among proteases, signaling proteins, CAZymes, and secreted proteins. There was also a strong overrepresentation of transcription factors among positively selected genes. This overrepresentation was still apparent after two complementary controls for detection bias due to sequence length. Positively selected sites were depleted within DNA-binding domains, suggesting changes in transcriptional responses to internal and external cues or protein–protein interactions have undergone positive selection more frequently than changes in promoter fidelity.
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Affiliation(s)
- Mark C Derbyshire
- Centre for Crop and Disease Management, Curtin University, Perth, Western Australia, Australia
| | - Lincoln A Harper
- Centre for Crop and Disease Management, Curtin University, Perth, Western Australia, Australia
| | - Francisco J Lopez-Ruiz
- Centre for Crop and Disease Management, Curtin University, Perth, Western Australia, Australia
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12
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Soyer JL, Clairet C, Gay EJ, Lapalu N, Rouxel T, Stukenbrock EH, Fudal I. Genome-wide mapping of histone modifications during axenic growth in two species of Leptosphaeria maculans showing contrasting genomic organization. Chromosome Res 2021; 29:219-236. [PMID: 34018080 PMCID: PMC8159818 DOI: 10.1007/s10577-021-09658-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 02/16/2021] [Accepted: 03/03/2021] [Indexed: 12/25/2022]
Abstract
Leptosphaeria maculans 'brassicae' (Lmb) and Leptosphaeria maculans 'lepidii' (Lml) are closely related phytopathogenic species that exhibit a large macrosynteny but contrasting genome structure. Lmb has more than 30% of repeats clustered in large repeat-rich regions, while the Lml genome has only a small amount of evenly distributed repeats. Repeat-rich regions of Lmb are enriched in effector genes, expressed during plant infection. The distinct genome structures of Lmb and Lml provide an excellent model for comparing the organization of pathogenicity genes in relation to the chromatin landscape in two closely related phytopathogenic fungi. Here, we performed chromatin immunoprecipitation (ChIP) during axenic culture, targeting histone modifications typical for heterochromatin or euchromatin, combined with transcriptomic analysis to analyze the influence of chromatin organization on gene expression. In both species, we found that facultative heterochromatin is enriched with genes lacking functional annotation, including numerous effector and species-specific genes. Notably, orthologous genes located in H3K27me3 domains are enriched with effector genes. Compared to other fungal species, including Lml, Lmb is distinct in having large H3K9me3 domains associated with repeat-rich regions that contain numerous species-specific effector genes. Discovery of these two distinctive heterochromatin landscapes now raises questions about their involvement in the regulation of pathogenicity, the dynamics of these domains during plant infection and the selective advantage to the fungus to host effector genes in H3K9me3 or H3K27me3 domains.
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Affiliation(s)
- Jessica L Soyer
- Université Paris-Saclay, INRAE, AgroParisTech, UMR BIOGER, 78850, Thiverval-Grignon, France.
- Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306, Plön, Germany.
- Christian-Albrechts University of Kiel, Am Botanischen Garten 1-9, 24118, Kiel, Germany.
| | - Colin Clairet
- Université Paris-Saclay, INRAE, AgroParisTech, UMR BIOGER, 78850, Thiverval-Grignon, France
| | - Elise J Gay
- Université Paris-Saclay, INRAE, AgroParisTech, UMR BIOGER, 78850, Thiverval-Grignon, France
| | - Nicolas Lapalu
- Université Paris-Saclay, INRAE, AgroParisTech, UMR BIOGER, 78850, Thiverval-Grignon, France
| | - Thierry Rouxel
- Université Paris-Saclay, INRAE, AgroParisTech, UMR BIOGER, 78850, Thiverval-Grignon, France
| | - Eva H Stukenbrock
- Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306, Plön, Germany
- Christian-Albrechts University of Kiel, Am Botanischen Garten 1-9, 24118, Kiel, Germany
| | - Isabelle Fudal
- Université Paris-Saclay, INRAE, AgroParisTech, UMR BIOGER, 78850, Thiverval-Grignon, France
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13
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Schweizer G, Haider MB, Barroso GV, Rössel N, Münch K, Kahmann R, Dutheil JY. Population Genomics of the Maize Pathogen Ustilago maydis: Demographic History and Role of Virulence Clusters in Adaptation. Genome Biol Evol 2021; 13:evab073. [PMID: 33837781 PMCID: PMC8120014 DOI: 10.1093/gbe/evab073] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/06/2021] [Indexed: 11/14/2022] Open
Abstract
The tight interaction between pathogens and their hosts results in reciprocal selective forces that impact the genetic diversity of the interacting species. The footprints of this selection differ between pathosystems because of distinct life-history traits, demographic histories, or genome architectures. Here, we studied the genome-wide patterns of genetic diversity of 22 isolates of the causative agent of the corn smut disease, Ustilago maydis, originating from five locations in Mexico, the presumed center of origin of this species. In this species, many genes encoding secreted effector proteins reside in so-called virulence clusters in the genome, an arrangement that is so far not found in other filamentous plant pathogens. Using a combination of population genomic statistical analyses, we assessed the geographical, historical, and genome-wide variation of genetic diversity in this fungal pathogen. We report evidence of two partially admixed subpopulations that are only loosely associated with geographic origin. Using the multiple sequentially Markov coalescent model, we inferred the demographic history of the two pathogen subpopulations over the last 0.5 Myr. We show that both populations experienced a recent strong bottleneck starting around 10,000 years ago, coinciding with the assumed time of maize domestication. Although the genome average genetic diversity is low compared with other fungal pathogens, we estimated that the rate of nonsynonymous adaptive substitutions is three times higher in genes located within virulence clusters compared with nonclustered genes, including nonclustered effector genes. These results highlight the role that these singular genomic regions play in the evolution of this pathogen.
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Affiliation(s)
- Gabriel Schweizer
- Department of Organismic Interactions, Max-Planck-Institute for Terrestrial Microbiology, Marburg, Germany
| | - Muhammad Bilal Haider
- Max-Planck-Institute for Evolutionary Biology, Research Group Molecular Systems Evolution, Plön, Germany
| | - Gustavo V Barroso
- Max-Planck-Institute for Evolutionary Biology, Research Group Molecular Systems Evolution, Plön, Germany
| | - Nicole Rössel
- Department of Organismic Interactions, Max-Planck-Institute for Terrestrial Microbiology, Marburg, Germany
| | - Karin Münch
- Department of Organismic Interactions, Max-Planck-Institute for Terrestrial Microbiology, Marburg, Germany
| | - Regine Kahmann
- Department of Organismic Interactions, Max-Planck-Institute for Terrestrial Microbiology, Marburg, Germany
| | - Julien Y Dutheil
- Department of Organismic Interactions, Max-Planck-Institute for Terrestrial Microbiology, Marburg, Germany
- Max-Planck-Institute for Evolutionary Biology, Research Group Molecular Systems Evolution, Plön, Germany
- Institute of Evolutionary Sciences of Montpellier, University of Montpellier 2, France
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14
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Peterson D, Li T, Calvo AM, Yin Y. Categorization of Orthologous Gene Clusters in 92 Ascomycota Genomes Reveals Functions Important for Phytopathogenicity. J Fungi (Basel) 2021; 7:337. [PMID: 33925458 PMCID: PMC8146833 DOI: 10.3390/jof7050337] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 04/23/2021] [Accepted: 04/24/2021] [Indexed: 01/01/2023] Open
Abstract
Phytopathogenic Ascomycota are responsible for substantial economic losses each year, destroying valuable crops. The present study aims to provide new insights into phytopathogenicity in Ascomycota from a comparative genomic perspective. This has been achieved by categorizing orthologous gene groups (orthogroups) from 68 phytopathogenic and 24 non-phytopathogenic Ascomycota genomes into three classes: Core, (pathogen or non-pathogen) group-specific, and genome-specific accessory orthogroups. We found that (i) ~20% orthogroups are group-specific and accessory in the 92 Ascomycota genomes, (ii) phytopathogenicity is not phylogenetically determined, (iii) group-specific orthogroups have more enriched functional terms than accessory orthogroups and this trend is particularly evident in phytopathogenic fungi, (iv) secreted proteins with signal peptides and horizontal gene transfers (HGTs) are the two functional terms that show the highest occurrence and significance in group-specific orthogroups, (v) a number of other functional terms are also identified to have higher significance and occurrence in group-specific orthogroups. Overall, our comparative genomics analysis determined positive enrichment existing between orthogroup classes and revealed a prediction of what genomic characteristics make an Ascomycete phytopathogenic. We conclude that genes shared by multiple phytopathogenic genomes are more important for phytopathogenicity than those that are unique in each genome.
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Affiliation(s)
- Daniel Peterson
- Department of Biological Sciences, Northern Illinois University, DeKalb, IL 60115, USA;
| | - Tang Li
- Nebraska Food for Health Center, Department of Food Science and Technology, University of Nebraska–Lincoln, Lincoln, NE 68588, USA;
| | - Ana M. Calvo
- Department of Biological Sciences, Northern Illinois University, DeKalb, IL 60115, USA;
| | - Yanbin Yin
- Nebraska Food for Health Center, Department of Food Science and Technology, University of Nebraska–Lincoln, Lincoln, NE 68588, USA;
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15
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Tralamazza SM, Piacentini KC, Savi GD, Carnielli-Queiroz L, de Carvalho Fontes L, Martins CS, Corrêa B, Rocha LO. Wild rice (O. latifolia) from natural ecosystems in the Pantanal region of Brazil: Host to Fusarium incarnatum-equiseti species complex and highly contaminated by zearalenone. Int J Food Microbiol 2021; 345:109127. [PMID: 33689972 DOI: 10.1016/j.ijfoodmicro.2021.109127] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 02/04/2021] [Accepted: 02/21/2021] [Indexed: 11/15/2022]
Abstract
We assessed the mycobiota diversity and mycotoxin levels present in wild rice (Oryza latifolia) from the Pantanal region of Brazil; fundamental aspects of which are severely understudied as an edible plant from a natural ecosystem. We found multiple fungal species contaminating the rice samples; the most frequent genera being Fusarium, Nigrospora and Cladosporium (35.9%, 26.1% and 15%, respectively). Within the Fusarium genus, the wild rice samples were mostly contaminated by the Fusarium incarnatum-equiseti species complex (FIESC) (80%) along with Fusarium fujikuroi species complex (20%). Phylogenetic analysis supported multiple FIESC species and gave support to the presence of two putative new groups within the complex (LN1 and LN2). Deoxynivalenol (DON) and zearalenone (ZEN) chemical analysis showed that most of the isolates were DON/ZEN producers and some were defined as high ZEN producers, displaying abundant ZEN levels over DON (over 19 times more). Suggesting that ZEN likely has a key adaptive role for FIESC in wild rice (O. latifolia). Mycotoxin determination in the rice samples revealed high frequency of ZEN, and 85% of rice samples had levels >100 μg/kg; the recommended limit set by regulatory agencies. DON was only detected in 5.2% of the samples. Our data shows that FIESC species are the main source of ZEN contamination in wild rice and the excessive levels of ZEN found in the rice samples raises considerable safety concerns regarding wild rice consumption by humans and animals.
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Affiliation(s)
- Sabina Moser Tralamazza
- Department of Microbiology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil.
| | - Karim Cristina Piacentini
- Department of Microbiology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Geovana Dagostim Savi
- University of Southern Santa Catarina (UNESC), Scientific and Technological Park, Santa Catarina, Brazil
| | - Lorena Carnielli-Queiroz
- Department of Microbiology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Lívia de Carvalho Fontes
- Department of Microbiology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | | | - Benedito Corrêa
- Department of Microbiology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Liliana Oliveira Rocha
- Department of Food Science, Food Engineering Faculty, University of Campinas, Campinas, Brazil.
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16
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Möller M, Habig M, Lorrain C, Feurtey A, Haueisen J, Fagundes WC, Alizadeh A, Freitag M, Stukenbrock EH. Recent loss of the Dim2 DNA methyltransferase decreases mutation rate in repeats and changes evolutionary trajectory in a fungal pathogen. PLoS Genet 2021; 17:e1009448. [PMID: 33750960 PMCID: PMC8016269 DOI: 10.1371/journal.pgen.1009448] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 04/01/2021] [Accepted: 02/26/2021] [Indexed: 01/04/2023] Open
Abstract
DNA methylation is found throughout all domains of life, yet the extent and function of DNA methylation differ among eukaryotes. Strains of the plant pathogenic fungus Zymoseptoria tritici appeared to lack cytosine DNA methylation (5mC) because gene amplification followed by Repeat-Induced Point mutation (RIP) resulted in the inactivation of the dim2 DNA methyltransferase gene. 5mC is, however, present in closely related sister species. We demonstrate that inactivation of dim2 occurred recently as some Z. tritici isolates carry a functional dim2 gene. Moreover, we show that dim2 inactivation occurred by a different path than previously hypothesized. We mapped the genome-wide distribution of 5mC in strains with or without functional dim2 alleles. Presence of functional dim2 correlates with high levels of 5mC in transposable elements (TEs), suggesting a role in genome defense. We identified low levels of 5mC in strains carrying non-functional dim2 alleles, suggesting that 5mC is maintained over time, presumably by an active Dnmt5 DNA methyltransferase. Integration of a functional dim2 allele in strains with mutated dim2 restored normal 5mC levels, demonstrating de novo cytosine methylation activity of Dim2. To assess the importance of 5mC for genome evolution, we performed an evolution experiment, comparing genomes of strains with high levels of 5mC to genomes of strains lacking functional dim2. We found that presence of a functional dim2 allele alters nucleotide composition by promoting C to T transitions (C→T) specifically at CpA (CA) sites during mitosis, likely contributing to TE inactivation. Our results show that 5mC density at TEs is a polymorphic trait in Z. tritici populations that can impact genome evolution.
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Affiliation(s)
- Mareike Möller
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Michael Habig
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Cécile Lorrain
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Alice Feurtey
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Janine Haueisen
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Wagner C. Fagundes
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Alireza Alizadeh
- Department of Plant Protection, Faculty of Agriculture, Azarbaijan Shahid Madani University, Tabriz, Iran
| | - Michael Freitag
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR, United States of America
| | - Eva H. Stukenbrock
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
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17
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Eschenbrenner CJ, Feurtey A, Stukenbrock EH. Population Genomics of Fungal Plant Pathogens and the Analyses of Rapidly Evolving Genome Compartments. Methods Mol Biol 2021; 2090:337-355. [PMID: 31975174 DOI: 10.1007/978-1-0716-0199-0_14] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Genome sequencing of fungal pathogens have documented extensive variation in genome structure and composition between species and in many cases between individuals of the same species. This type of genomic variation can be adaptive for pathogens to rapidly evolve new virulence phenotypes. Analyses of genome-wide variation in fungal pathogen genomes rely on high quality assemblies and methods to detect and quantify structural variation. Population genomic studies in fungi have addressed the underlying mechanisms whereby structural variation can be rapidly generated. Transposable elements, high mutation and recombination rates as well as incorrect chromosome segregation during mitosis and meiosis contribute to extensive variation observed in many species. We here summarize key findings in the field of fungal pathogen genomics and we discuss methods to detect and characterize structural variants including an alignment-based pipeline to study variation in population genomic data.
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Affiliation(s)
- Christoph J Eschenbrenner
- Environmental Genomics, Christian-Albrechts University of Kiel, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Alice Feurtey
- Environmental Genomics, Christian-Albrechts University of Kiel, Kiel, Germany
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Eva H Stukenbrock
- Environmental Genomics, Christian-Albrechts University of Kiel, Kiel, Germany.
- Max Planck Institute for Evolutionary Biology, Plön, Germany.
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18
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Hessenauer P, Feau N, Gill U, Schwessinger B, Brar GS, Hamelin RC. Evolution and Adaptation of Forest and Crop Pathogens in the Anthropocene. PHYTOPATHOLOGY 2021; 111:49-67. [PMID: 33200962 DOI: 10.1094/phyto-08-20-0358-fi] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Anthropocene marks the era when human activity is making a significant impact on earth, its ecological and biogeographical systems. The domestication and intensification of agricultural and forest production systems have had a large impact on plant and tree health. Some pathogens benefitted from these human activities and have evolved and adapted in response to the expansion of crop and forest systems, resulting in global outbreaks. Global pathogen genomics data including population genomics and high-quality reference assemblies are crucial for understanding the evolution and adaptation of pathogens. Crops and forest trees have remarkably different characteristics, such as reproductive time and the level of domestication. They also have different production systems for disease management with more intensive management in crops than forest trees. By comparing and contrasting results from pathogen population genomic studies done on widely different agricultural and forest production systems, we can improve our understanding of pathogen evolution and adaptation to different selection pressures. We find that in spite of these differences, similar processes such as hybridization, host jumps, selection, specialization, and clonal expansion are shaping the pathogen populations in both crops and forest trees. We propose some solutions to reduce these impacts and lower the probability of global pathogen outbreaks so that we can envision better management strategies to sustain global food production as well as ecosystem services.
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Affiliation(s)
- Pauline Hessenauer
- Faculty of Forestry, Geography and Geomatics, Laval University, Quebec City, QC, G1V 0A6 Canada
| | - Nicolas Feau
- Faculty of Forestry, The University of British Columbia, Vancouver, BC, V6T 1Z4 Canada
| | - Upinder Gill
- College of Agriculture, Food Systems, and Natural Resources, North Dakota State University, Fargo, ND 58102, U.S.A
| | - Benjamin Schwessinger
- Research School of Biology, Australian National University, Acton, ACT 2601 Australia
| | - Gurcharn S Brar
- Faculty of Land and Food Systems, The University of British Columbia, Vancouver, BC, V6T 1Z4 Canada
| | - Richard C Hamelin
- Faculty of Forestry, Geography and Geomatics, Laval University, Quebec City, QC, G1V 0A6 Canada
- Faculty of Forestry, The University of British Columbia, Vancouver, BC, V6T 1Z4 Canada
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19
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Everhart S, Gambhir N, Stam R. Population Genomics of Filamentous Plant Pathogens-A Brief Overview of Research Questions, Approaches, and Pitfalls. PHYTOPATHOLOGY 2021; 111:12-22. [PMID: 33337245 DOI: 10.1094/phyto-11-20-0527-fi] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
With ever-decreasing sequencing costs, research on the population biology of plant pathogens is transitioning from population genetics-using dozens of genetic markers or polymorphism data of several genes-to population genomics-using several hundred to tens of thousands of markers or whole-genome sequence data. The field of population genomics is characterized by rapid theoretical and methodological advances and by numerous steps and pitfalls in its technical and analytical workflow. In this article, we aim to provide a brief overview of topics relevant to the study of population genomics of filamentous plant pathogens and direct readers to more extensive reviews for in-depth understanding. We briefly discuss different types of population genomics-inspired research questions and give insights into the sampling strategies that can be used to answer such questions. We then consider different sequencing strategies, the various options available for data processing, and some of the currently available tools for population genomic data analysis. We conclude by highlighting some of the hurdles along the population genomic workflow, providing cautionary warnings relative to assumptions and technical challenges, and presenting our own future perspectives of the field of population genomics for filamentous plant pathogens.
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Affiliation(s)
- Sydney Everhart
- Department of Plant Pathology, University of Nebraska, Lincoln, NE 68583, U.S.A
| | - Nikita Gambhir
- Department of Plant Pathology, University of Nebraska, Lincoln, NE 68583, U.S.A
| | - Remco Stam
- Phytopathology, School of Life Sciences Weihenstephan, Technical University Munich, Germany
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20
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Ghosh PN, Brookes LM, Edwards HM, Fisher MC, Jervis P, Kappel D, Sewell TR, Shelton JM, Skelly E, Rhodes JL. Cross-Disciplinary Genomics Approaches to Studying Emerging Fungal Infections. Life (Basel) 2020; 10:E315. [PMID: 33260763 PMCID: PMC7761180 DOI: 10.3390/life10120315] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 11/15/2020] [Accepted: 11/19/2020] [Indexed: 11/16/2022] Open
Abstract
Emerging fungal pathogens pose a serious, global and growing threat to food supply systems, wild ecosystems, and human health. However, historic chronic underinvestment in their research has resulted in a limited understanding of their epidemiology relative to bacterial and viral pathogens. Therefore, the untargeted nature of genomics and, more widely, -omics approaches is particularly attractive in addressing the threats posed by and illuminating the biology of these pathogens. Typically, research into plant, human and wildlife mycoses have been largely separated, with limited dialogue between disciplines. However, many serious mycoses facing the world today have common traits irrespective of host species, such as plastic genomes; wide host ranges; large population sizes and an ability to persist outside the host. These commonalities mean that -omics approaches that have been productively applied in one sphere and may also provide important insights in others, where these approaches may have historically been underutilised. In this review, we consider the advances made with genomics approaches in the fields of plant pathology, human medicine and wildlife health and the progress made in linking genomes to other -omics datatypes and sets; we identify the current barriers to linking -omics approaches and how these are being underutilised in each field; and we consider how and which -omics methodologies it is most crucial to build capacity for in the near future.
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Affiliation(s)
- Pria N. Ghosh
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, St Mary’s Campus, Imperial College London, London W2 1PG, UK; (L.M.B.); (H.M.E.); (M.C.F.); (P.J.); (D.K.); (T.R.S.); (J.M.G.S.); (E.S.); (J.L.R.)
- Unit for Environmental Sciences and Management, North-West University, Potchefstroom 2520, South Africa
| | - Lola M. Brookes
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, St Mary’s Campus, Imperial College London, London W2 1PG, UK; (L.M.B.); (H.M.E.); (M.C.F.); (P.J.); (D.K.); (T.R.S.); (J.M.G.S.); (E.S.); (J.L.R.)
- Institute of Zoology, Zoological Society of London, London NW1 4RY, UK
- Royal Veterinary College, Hawkshead Lane, North Mymms, Herts AL9 7TA, UK
| | - Hannah M. Edwards
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, St Mary’s Campus, Imperial College London, London W2 1PG, UK; (L.M.B.); (H.M.E.); (M.C.F.); (P.J.); (D.K.); (T.R.S.); (J.M.G.S.); (E.S.); (J.L.R.)
| | - Matthew C. Fisher
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, St Mary’s Campus, Imperial College London, London W2 1PG, UK; (L.M.B.); (H.M.E.); (M.C.F.); (P.J.); (D.K.); (T.R.S.); (J.M.G.S.); (E.S.); (J.L.R.)
| | - Phillip Jervis
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, St Mary’s Campus, Imperial College London, London W2 1PG, UK; (L.M.B.); (H.M.E.); (M.C.F.); (P.J.); (D.K.); (T.R.S.); (J.M.G.S.); (E.S.); (J.L.R.)
- Institute of Zoology, Zoological Society of London, London NW1 4RY, UK
- Department of Chemistry, University College London, London WC1H 0AJ, UK
| | - Dana Kappel
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, St Mary’s Campus, Imperial College London, London W2 1PG, UK; (L.M.B.); (H.M.E.); (M.C.F.); (P.J.); (D.K.); (T.R.S.); (J.M.G.S.); (E.S.); (J.L.R.)
| | - Thomas R. Sewell
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, St Mary’s Campus, Imperial College London, London W2 1PG, UK; (L.M.B.); (H.M.E.); (M.C.F.); (P.J.); (D.K.); (T.R.S.); (J.M.G.S.); (E.S.); (J.L.R.)
| | - Jennifer M.G. Shelton
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, St Mary’s Campus, Imperial College London, London W2 1PG, UK; (L.M.B.); (H.M.E.); (M.C.F.); (P.J.); (D.K.); (T.R.S.); (J.M.G.S.); (E.S.); (J.L.R.)
- UK Centre for Ecology & Hydrology, Wallingford OX10 8BB, UK
| | - Emily Skelly
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, St Mary’s Campus, Imperial College London, London W2 1PG, UK; (L.M.B.); (H.M.E.); (M.C.F.); (P.J.); (D.K.); (T.R.S.); (J.M.G.S.); (E.S.); (J.L.R.)
| | - Johanna L. Rhodes
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, St Mary’s Campus, Imperial College London, London W2 1PG, UK; (L.M.B.); (H.M.E.); (M.C.F.); (P.J.); (D.K.); (T.R.S.); (J.M.G.S.); (E.S.); (J.L.R.)
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21
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Hartmann FE, Vonlanthen T, Singh NK, McDonald MC, Milgate A, Croll D. The complex genomic basis of rapid convergent adaptation to pesticides across continents in a fungal plant pathogen. Mol Ecol 2020; 30:5390-5405. [PMID: 33211369 DOI: 10.1111/mec.15737] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/30/2020] [Accepted: 11/12/2020] [Indexed: 12/12/2022]
Abstract
Convergent evolution leads to identical phenotypic traits in different species or populations. Convergence can be driven by standing variation allowing selection to favour identical alleles in parallel or the same mutations can arise independently. However, the molecular basis of such convergent adaptation remains often poorly resolved. Pesticide resistance in agricultural ecosystems is a hallmark of convergence in phenotypic traits. Here, we analyse the major fungal pathogen Zymoseptoria tritici causing serious losses on wheat and with fungicide resistance emergence across several continents. We sampled three population pairs each from a different continent spanning periods early and late in the application of fungicides. To identify causal loci for resistance, we combined knowledge from molecular genetics work and performed genome-wide association studies (GWAS) on a global set of isolates. We discovered yet unknown factors in azole resistance including a gene encoding membrane associated functions. We found strong support for the "hotspot" model of resistance evolution with convergent changes in a small set of loci but additional loci showed more population-specific allele frequency changes. Genome-wide scans of selection showed that half of all known resistance loci were overlapping a selective sweep region. Hence, the application of fungicides was one of the major selective agents acting on the pathogen over the past decades. Furthermore, loci identified through GWAS showed the highest overlap with selective sweep regions underlining the importance to map phenotypic trait variation in evolving populations. Our population genomic analyses highlighted that both de novo mutations and gene flow contributed to convergent pesticide adaptation.
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Affiliation(s)
- Fanny E Hartmann
- Ecologie Systematique Evolution, Batiment 360, Université Paris-Saclay, AgroParisTech, CNRS, Orsay, France.,Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
| | - Tiziana Vonlanthen
- Plant Pathology, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland.,Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Nikhil Kumar Singh
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Megan C McDonald
- Division of Plant Science, Research School of Biology, The Australian National University, Canberra, ACT, Australia.,School of Biosciences, University of Birmingham, Birmingham, UK
| | - Andrew Milgate
- NSW Department of Primary Industries, Wagga Wagga Agricultural Institute, Wagga Wagga, NSW, Australia
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
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22
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Comparative Genomics Analyses of Lifestyle Transitions at the Origin of an Invasive Fungal Pathogen in the Genus Cryphonectria. mSphere 2020; 5:5/5/e00737-20. [PMID: 33055257 PMCID: PMC7565894 DOI: 10.1128/msphere.00737-20] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Forest and agroecosystems, as well as animal and human health, are threatened by emerging pathogens. Following decimation of chestnuts in the United States, the fungal pathogen Cryphonectria parasitica colonized Europe. After establishment, the pathogen population gave rise to a highly successful lineage that spread rapidly across the continent. Core to our understanding of what makes a successful pathogen is the genetic repertoire enabling the colonization and exploitation of host species. Here, we have assembled >100 genomes across two related genera to identify key genomic determinants leading to the emergence of chestnut blight. We found subtle yet highly specific changes in the transition from saprotrophy to latent pathogenicity mostly determined by enzymes involved in carbohydrate metabolism. Large-scale genomic analyses of genes underlying key nutrition modes can facilitate the detection of species with the potential to emerge as pathogens. Emerging fungal pathogens are a threat to forest and agroecosystems, as well as animal and human health. How pathogens evolve from nonpathogenic ancestors is still poorly understood, making the prediction of future outbreaks challenging. Most pathogens have evolved lifestyle adaptations, which were enabled by specific changes in the gene content of the species. Hence, understanding transitions in the functions encoded by genomes gives valuable insight into the evolution of pathogenicity. Here, we studied lifestyle evolution in the genus Cryphonectria, including the prominent invasive pathogen Cryphonectria parasitica, the causal agent of chestnut blight on Castanea species. We assembled and compared the genomes of pathogenic and putatively nonpathogenic Cryphonectria species, as well as sister group pathogens in the family Cryphonectriaceae (Diaporthales, Ascomycetes), to investigate the evolution of genome size and gene content. We found a striking loss of genes associated with carbohydrate metabolism (CAZymes) in C. parasitica compared to other Cryphonectriaceae. Despite substantial CAZyme gene loss, experimental data suggest that C. parasitica has retained wood colonization abilities shared with other Cryphonectria species. Putative effectors substantially varied in number, cysteine content, and protein length among species. In contrast, secondary metabolite gene clusters show a high degree of conservation within the genus. Overall, our results underpin the recent lifestyle transition of C. parasitica toward a more pathogenic lifestyle. Our findings suggest that a CAZyme loss may have promoted pathogenicity of C. parasitica on Castanea species. Analyzing gene complements underlying key nutrition modes can facilitate the detection of species with the potential to emerge as pathogens. IMPORTANCE Forest and agroecosystems, as well as animal and human health, are threatened by emerging pathogens. Following decimation of chestnuts in the United States, the fungal pathogen Cryphonectria parasitica colonized Europe. After establishment, the pathogen population gave rise to a highly successful lineage that spread rapidly across the continent. Core to our understanding of what makes a successful pathogen is the genetic repertoire enabling the colonization and exploitation of host species. Here, we have assembled >100 genomes across two related genera to identify key genomic determinants leading to the emergence of chestnut blight. We found subtle yet highly specific changes in the transition from saprotrophy to latent pathogenicity mostly determined by enzymes involved in carbohydrate metabolism. Large-scale genomic analyses of genes underlying key nutrition modes can facilitate the detection of species with the potential to emerge as pathogens.
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23
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Naranjo‐Ortiz MA, Gabaldón T. Fungal evolution: cellular, genomic and metabolic complexity. Biol Rev Camb Philos Soc 2020; 95:1198-1232. [PMID: 32301582 PMCID: PMC7539958 DOI: 10.1111/brv.12605] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 03/31/2020] [Accepted: 04/02/2020] [Indexed: 12/13/2022]
Abstract
The question of how phenotypic and genomic complexity are inter-related and how they are shaped through evolution is a central question in biology that historically has been approached from the perspective of animals and plants. In recent years, however, fungi have emerged as a promising alternative system to address such questions. Key to their ecological success, fungi present a broad and diverse range of phenotypic traits. Fungal cells can adopt many different shapes, often within a single species, providing them with great adaptive potential. Fungal cellular organizations span from unicellular forms to complex, macroscopic multicellularity, with multiple transitions to higher or lower levels of cellular complexity occurring throughout the evolutionary history of fungi. Similarly, fungal genomes are very diverse in their architecture. Deep changes in genome organization can occur very quickly, and these phenomena are known to mediate rapid adaptations to environmental changes. Finally, the biochemical complexity of fungi is huge, particularly with regard to their secondary metabolites, chemical products that mediate many aspects of fungal biology, including ecological interactions. Herein, we explore how the interplay of these cellular, genomic and metabolic traits mediates the emergence of complex phenotypes, and how this complexity is shaped throughout the evolutionary history of Fungi.
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Affiliation(s)
- Miguel A. Naranjo‐Ortiz
- Bioinformatics and Genomics Programme, Centre for Genomic Regulation (CRG)The Barcelona Institute of Science and TechnologyDr. Aiguader 88, Barcelona08003Spain
| | - Toni Gabaldón
- Bioinformatics and Genomics Programme, Centre for Genomic Regulation (CRG)The Barcelona Institute of Science and TechnologyDr. Aiguader 88, Barcelona08003Spain
- Department of Experimental Sciences, Universitat Pompeu Fabra (UPF)Dr. Aiguader 88, 08003BarcelonaSpain
- ICREAPg. Lluís Companys 23, 08010BarcelonaSpain
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24
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Crandall SG, Gold KM, Jiménez-Gasco MDM, Filgueiras CC, Willett DS. A multi-omics approach to solving problems in plant disease ecology. PLoS One 2020; 15:e0237975. [PMID: 32960892 PMCID: PMC7508392 DOI: 10.1371/journal.pone.0237975] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 08/04/2020] [Indexed: 12/11/2022] Open
Abstract
The swift rise of omics-approaches allows for investigating microbial diversity and plant-microbe interactions across diverse ecological communities and spatio-temporal scales. The environment, however, is rapidly changing. The introduction of invasive species and the effects of climate change have particular impact on emerging plant diseases and managing current epidemics. It is critical, therefore, to take a holistic approach to understand how and why pathogenesis occurs in order to effectively manage for diseases given the synergies of changing environmental conditions. A multi-omics approach allows for a detailed picture of plant-microbial interactions and can ultimately allow us to build predictive models for how microbes and plants will respond to stress under environmental change. This article is designed as a primer for those interested in integrating -omic approaches into their plant disease research. We review -omics technologies salient to pathology including metabolomics, genomics, metagenomics, volatilomics, and spectranomics, and present cases where multi-omics have been successfully used for plant disease ecology. We then discuss additional limitations and pitfalls to be wary of prior to conducting an integrated research project as well as provide information about promising future directions.
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Affiliation(s)
- Sharifa G. Crandall
- Department of Plant Pathology and Environmental Microbiology, The Pennsylvania State University, University Park, PA, United States of America
| | - Kaitlin M. Gold
- Plant Pathology & Plant Microbe Biology Section, Cornell AgriTech, Cornell University, Geneva, NY, United States of America
| | - María del Mar Jiménez-Gasco
- Department of Plant Pathology and Environmental Microbiology, The Pennsylvania State University, University Park, PA, United States of America
| | - Camila C. Filgueiras
- Applied Chemical Ecology Technology, Cornell AgriTech, Cornell University, Geneva, NY, United States of America
| | - Denis S. Willett
- Applied Chemical Ecology Technology, Cornell AgriTech, Cornell University, Geneva, NY, United States of America
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25
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Benbow HR, Brennan CJ, Zhou B, Christodoulou T, Berry S, Uauy C, Mullins E, Doohan FM. Insights into the resistance of a synthetically-derived wheat to Septoria tritici blotch disease: less is more. BMC PLANT BIOLOGY 2020; 20:407. [PMID: 32883202 PMCID: PMC7469286 DOI: 10.1186/s12870-020-02612-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 08/18/2020] [Indexed: 05/30/2023]
Abstract
BACKGROUND Little is known about the initial, symptomless (latent) phase of the devastating wheat disease Septoria tritici blotch. However, speculations as to its impact on fungal success and disease severity in the field have suggested that a long latent phase is beneficial to the host and can reduce inoculum build up in the field over a growing season. The winter wheat cultivar Stigg is derived from a synthetic hexaploid wheat and contains introgressions from wild tetraploid wheat Triticum turgidum subsp. dicoccoides, which contribute to cv. Stigg's exceptional STB resistance, hallmarked by a long latent phase. We compared the early transcriptomic response to Zymoseptoria tritici of cv. Stigg to a susceptible wheat cultivar, to elucidate the mechanisms of and differences in pathogen recognition and disease response in these two hosts. RESULTS The STB-susceptible cultivar Longbow responds to Z. tritici infection with a stress response, including activation of hormone-responsive transcription factors, post translational modifications, and response to oxidative stress. The activation of key genes associated with these pathways in cv. Longbow was independently observed in a second susceptible wheat cultivar based on an independent gene expression study. By comparison, cv. Stigg is apathetic in response to STB, and appears to fail to activate a range of defence pathways that cv. Longbow employs. Stigg also displays some evidence of sub-genome bias in its response to Z. tritici infection, whereas the susceptible cv. Longbow shows even distribution of Z. tritici responsive genes across the three wheat sub-genomes. CONCLUSIONS We identify a suite of disease response genes that are involved in early pathogen response in susceptible wheat cultivars that may ultimately lead to susceptibility. In comparison, we hypothesise that rather than an active defence response to stave off disease progression, cv. Stigg's defence strategy is molecular lethargy, or a lower-amplitude of pathogen recognition that may stem from cv. Stigg's wild wheat-derived ancestry. Overall, we present insights into cv. Stigg's exceptional resistance to STB, and present key biological processes for further characterisation in this pathosystem.
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Affiliation(s)
- Harriet R Benbow
- UCD School of Biology and Environmental Science, University College Dublin, UCD Belfield, Dublin 4, Ireland
- UCD Earth Institute, University College Dublin, UCD Belfield, Dublin 4, Ireland
- UCD Centre for Plant Science, University College Dublin, UCD Belfield, Dublin 4, Ireland
| | - Ciarán J Brennan
- UCD School of Biology and Environmental Science, University College Dublin, UCD Belfield, Dublin 4, Ireland
- UCD Earth Institute, University College Dublin, UCD Belfield, Dublin 4, Ireland
- UCD Centre for Plant Science, University College Dublin, UCD Belfield, Dublin 4, Ireland
| | - Binbin Zhou
- UCD School of Biology and Environmental Science, University College Dublin, UCD Belfield, Dublin 4, Ireland
- UCD Earth Institute, University College Dublin, UCD Belfield, Dublin 4, Ireland
- UCD Centre for Plant Science, University College Dublin, UCD Belfield, Dublin 4, Ireland
| | - Thalia Christodoulou
- UCD School of Biology and Environmental Science, University College Dublin, UCD Belfield, Dublin 4, Ireland
- UCD Earth Institute, University College Dublin, UCD Belfield, Dublin 4, Ireland
- UCD Centre for Plant Science, University College Dublin, UCD Belfield, Dublin 4, Ireland
| | - Simon Berry
- Limagrain UK Ltd, Windmill Avenue, Woolpit, Suffolk, IP30 9UP, UK
| | | | - Ewen Mullins
- Teagasc Crops Research, Oak Park, Co. Carlow, Ireland
| | - Fiona M Doohan
- UCD School of Biology and Environmental Science, University College Dublin, UCD Belfield, Dublin 4, Ireland.
- UCD Earth Institute, University College Dublin, UCD Belfield, Dublin 4, Ireland.
- UCD Centre for Plant Science, University College Dublin, UCD Belfield, Dublin 4, Ireland.
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26
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Fones HN, Bebber DP, Chaloner TM, Kay WT, Steinberg G, Gurr SJ. Threats to global food security from emerging fungal and oomycete crop pathogens. ACTA ACUST UNITED AC 2020; 1:332-342. [PMID: 37128085 DOI: 10.1038/s43016-020-0075-0] [Citation(s) in RCA: 140] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 04/09/2020] [Indexed: 11/09/2022]
Abstract
Emerging fungal and oomycete pathogens infect staple calorie crops and economically important commodity crops, thereby posing a significant risk to global food security. Our current agricultural systems - with emphasis on intensive monoculture practices - and globalized markets drive the emergence and spread of new pathogens and problematic traits, such as fungicide resistance. Climate change further promotes the emergence of pathogens on new crops and in new places. Here we review the factors affecting the introduction and spread of pathogens and current disease control strategies, illustrating these with the historic example of the Irish potato famine and contemporary examples of soybean rust, wheat blast and blotch, banana wilt and cassava root rot. Our Review looks to the future, summarizing what we see as the main challenges and knowledge gaps, and highlighting the direction that research must take to face the challenge of emerging crop pathogens.
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27
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Derbyshire MC. Bioinformatic Detection of Positive Selection Pressure in Plant Pathogens: The Neutral Theory of Molecular Sequence Evolution in Action. Front Microbiol 2020; 11:644. [PMID: 32328056 PMCID: PMC7160247 DOI: 10.3389/fmicb.2020.00644] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 03/20/2020] [Indexed: 11/13/2022] Open
Abstract
The genomes of plant pathogenic fungi and oomycetes are often exposed to strong positive selection pressure. During speciation, shifts in host range and preference can lead to major adaptive changes. Furthermore, evolution of total host resistance to most isolates can force rapid evolutionary changes in host-specific pathogens. Crop pathogens are subjected to particularly intense selective pressures from monocultures and fungicides. Detection of the footprints of positive selection in plant pathogen genomes is a worthwhile endeavor as it aids understanding of the fundamental biology of these important organisms. There are two main classes of test for detection of positively selected alleles. Tests based on the ratio of non-synonymous to synonymous substitutions per site detect the footprints of multiple fixation events between divergent lineages. Thus, they are well-suited to the study of ancient adaptation events spanning speciations. On the other hand, tests that scan genomes for local fluctuations in allelic diversity within populations are suitable for detection of recent positive selection in populations. In this review, I briefly describe some of the more widely used tests of positive selection and the theory underlying them. I then discuss various examples of their application to plant pathogen genomes, emphasizing the types of genes that are associated with signatures of positive selection. I conclude with a discussion of the practicality of such tests for identification of pathogen genes of interest and the important features of pathogen ecology that must be taken into account for accurate interpretation.
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Affiliation(s)
- Mark C Derbyshire
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia
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28
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Feurtey A, Stevens DM, Stephan W, Stukenbrock EH. Interspecific Gene Exchange Introduces High Genetic Variability in Crop Pathogen. Genome Biol Evol 2020; 11:3095-3105. [PMID: 31603209 PMCID: PMC6836716 DOI: 10.1093/gbe/evz224] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/08/2019] [Indexed: 12/27/2022] Open
Abstract
Genome analyses have revealed a profound role of hybridization and introgression in the evolution of many eukaryote lineages, including fungi. The impact of recurrent introgression on fungal evolution however remains elusive. Here, we analyzed signatures of introgression along the genome of the fungal wheat pathogen Zymoseptoria tritici. We applied a comparative population genomics approach, including genome data from five Zymoseptoria species, to characterize the distribution and composition of introgressed regions representing segments with an exceptional haplotype pattern. These regions are found throughout the genome, comprising 5% of the total genome and overlapping with > 1,000 predicted genes. We performed window-based phylogenetic analyses along the genome to distinguish regions which have a monophyletic or nonmonophyletic origin with Z. tritici sequences. A majority of nonmonophyletic windows overlap with the highly variable regions suggesting that these originate from introgression. We verified that incongruent gene genealogies do not result from incomplete lineage sorting by comparing the observed and expected length distribution of haplotype blocks resulting from incomplete lineage sorting. Although protein-coding genes are not enriched in these regions, we identify 18 that encode putative virulence determinants. Moreover, we find an enrichment of transposable elements in these regions implying that hybridization may contribute to the horizontal spread of transposable elements. We detected a similar pattern in the closely related species Zymoseptoria ardabiliae, suggesting that hybridization is widespread among these closely related grass pathogens. Overall, our results demonstrate a significant impact of recurrent hybridization on overall genome evolution of this important wheat pathogen.
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Affiliation(s)
- Alice Feurtey
- Environmental Genomics, Max Planck Institute for Evolutionary Biology, Plön, Germany.,Botanical Institute, Christian-Albrechts University of Kiel, Germany
| | - Danielle M Stevens
- Environmental Genomics, Max Planck Institute for Evolutionary Biology, Plön, Germany.,Botanical Institute, Christian-Albrechts University of Kiel, Germany.,Department of Plant Pathology, University of California, Davis
| | - Wolfgang Stephan
- Leibniz Institute for Evolution and Biodiversity Science, Berlin, Germany
| | - Eva H Stukenbrock
- Environmental Genomics, Max Planck Institute for Evolutionary Biology, Plön, Germany.,Botanical Institute, Christian-Albrechts University of Kiel, Germany
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29
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Moutinho AF, Bataillon T, Dutheil JY. Variation of the adaptive substitution rate between species and within genomes. Evol Ecol 2019. [DOI: 10.1007/s10682-019-10026-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
AbstractThe importance of adaptive mutations in molecular evolution is extensively debated. Recent developments in population genomics allow inferring rates of adaptive mutations by fitting a distribution of fitness effects to the observed patterns of polymorphism and divergence at sites under selection and sites assumed to evolve neutrally. Here, we summarize the current state-of-the-art of these methods and review the factors that affect the molecular rate of adaptation. Several studies have reported extensive cross-species variation in the proportion of adaptive amino-acid substitutions (α) and predicted that species with larger effective population sizes undergo less genetic drift and higher rates of adaptation. Disentangling the rates of positive and negative selection, however, revealed that mutations with deleterious effects are the main driver of this population size effect and that adaptive substitution rates vary comparatively little across species. Conversely, rates of adaptive substitution have been documented to vary substantially within genomes. On a genome-wide scale, gene density, recombination and mutation rate were observed to play a role in shaping molecular rates of adaptation, as predicted under models of linked selection. At the gene level, it has been reported that the gene functional category and the macromolecular structure substantially impact the rate of adaptive mutations. Here, we deliver a comprehensive review of methods used to infer the molecular adaptive rate, the potential drivers of adaptive evolution and how positive selection shapes molecular evolution within genes, across genes within species and between species.
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30
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Stam R, Sghyer H, Tellier A, Hess M, Hückelhoven R. The Current Epidemic of the Barley Pathogen Ramularia collo-cygni Derives from a Population Expansion and Shows Global Admixture. PHYTOPATHOLOGY 2019; 109:2161-2168. [PMID: 31322487 DOI: 10.1094/phyto-04-19-0117-r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Ramularia leaf spot is becoming an ever-increasing problem in main barley-growing regions since the 1980s, causing up to 70% yield loss in extreme cases. Yet, the causal agent Ramularia collo-cygni remains poorly studied. The diversity of the pathogen in the field thus far remains unknown. Furthermore, it is unknown to what extent the pathogen has a sexual reproductive cycle. The teleomorph of R. collo-cygni has not been observed. To study the genetic diversity of R. collo-cygni and get more insights in its biology, we sequenced the genomes of 19 R. collo-cygni isolates from multiple geographic locations and diverse hosts. Nucleotide polymorphism analyses of all isolates shows that R. collo-cygni is genetically diverse worldwide, with little geographic or host specific differentiation. Next, we used two different methods to detect signals of recombination in our sample set. Both methods find putative recombination events, which indicate that sexual reproduction happens or has happened in the global R. collo-cygni population. Lastly, we used these data on recombination to perform historic population size analyses. These suggest that the effective population size of R. collo-cygni decreased during the domestication of barley and subsequently grew with the rise of agriculture. Our findings deepen our understanding of R. collo-cygni biology and can help us to understand the current epidemic. We discuss how our findings support possible global spread through seed transfer, and we highlight how recombination, clonal spreading, and lack of host specificity could amplify global epidemics of this increasingly important disease and suggest specific approaches to combat the pathogen.
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Affiliation(s)
- Remco Stam
- Chair of Phytopathology, School of Life Sciences Weihenstephan, Technical University of Munich, 85354 Freising, Germany
| | - Hind Sghyer
- Chair of Phytopathology, School of Life Sciences Weihenstephan, Technical University of Munich, 85354 Freising, Germany
| | - Aurélien Tellier
- Section of Population Genetics, School of Life Sciences Weihenstephan, Technical University of Munich, 85354 Freising, Germany
| | - Michael Hess
- Chair of Phytopathology, School of Life Sciences Weihenstephan, Technical University of Munich, 85354 Freising, Germany
| | - Ralph Hückelhoven
- Chair of Phytopathology, School of Life Sciences Weihenstephan, Technical University of Munich, 85354 Freising, Germany
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31
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Ametrano CG, Grewe F, Crous PW, Goodwin SB, Liang C, Selbmann L, Lumbsch HT, Leavitt SD, Muggia L. Genome-scale data resolve ancestral rock-inhabiting lifestyle in Dothideomycetes (Ascomycota). IMA Fungus 2019; 10:19. [PMID: 32647623 PMCID: PMC7325674 DOI: 10.1186/s43008-019-0018-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 09/11/2019] [Indexed: 12/31/2022] Open
Abstract
Dothideomycetes is the most diverse fungal class in Ascomycota and includes species with a wide range of lifestyles. Previous multilocus studies have investigated the taxonomic and evolutionary relationships of these taxa but often failed to resolve early diverging nodes and frequently generated inconsistent placements of some clades. Here, we use a phylogenomic approach to resolve relationships in Dothideomycetes, focusing on two genera of melanized, extremotolerant rock-inhabiting fungi, Lichenothelia and Saxomyces, that have been suggested to be early diverging lineages. We assembled phylogenomic datasets from newly sequenced (4) and previously available genomes (238) of 242 taxa. We explored the influence of tree inference methods, supermatrix vs. coalescent-based species tree, and the impact of varying amounts of genomic data. Overall, our phylogenetic reconstructions provide consistent and well-supported topologies for Dothideomycetes, recovering Lichenothelia and Saxomyces among the earliest diverging lineages in the class. In addition, many of the major lineages within Dothideomycetes are recovered as monophyletic, and the phylogenomic approach implemented strongly supports their relationships. Ancestral character state reconstruction suggest that the rock-inhabiting lifestyle is ancestral within the class.
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Affiliation(s)
- Claudio G Ametrano
- Department of Life Sciences, University of Trieste, via Giorgieri 10, 34127 Trieste, Italy
| | - Felix Grewe
- Grainger Bioinformatics Center and Integrative Research Center, Science and Education, Field Museum of Natural History, 1400 S Lake Shore Drive, Chicago, IL 60605 USA
| | - Pedro W Crous
- Westerdijk Fungal Biodiversity Institute, P.O. Box 85176, 3508 AD Utrecht, The Netherlands
| | - Stephen B Goodwin
- USDA-ARS, Crop Production and Pest Control Research Unit and Department of Botany and Plant Pathology, Purdue University, 915 West State Street, West Lafayette, IN 47907-2054 USA
| | - Chen Liang
- College of Plant Health and Medicine, Qingdao Agricultural University, Qingdao, 266109 China
| | - Laura Selbmann
- Department of Ecological and Biological Sciences, University of Tuscia, Largo dell' Università, 01100 Viterbo, Italy.,Italian National Antarctic Museum (MNA), Mycological Section, Genoa, Italy
| | - H Thorsten Lumbsch
- Grainger Bioinformatics Center and Integrative Research Center, Science and Education, Field Museum of Natural History, 1400 S Lake Shore Drive, Chicago, IL 60605 USA
| | - Steven D Leavitt
- Department of Biology and M.L. Bean Life Science Museum, Brigham Young University, 4102 Life Science Building, Provo, UT 84602 USA
| | - Lucia Muggia
- Department of Life Sciences, University of Trieste, via Giorgieri 10, 34127 Trieste, Italy
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32
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Yang H, Ma J, Rong Z, Zeng D, Wang Y, Hu S, Ye W, Zheng X. Wheat Straw Return Influences Nitrogen-Cycling and Pathogen Associated Soil Microbiota in a Wheat-Soybean Rotation System. Front Microbiol 2019; 10:1811. [PMID: 31440226 PMCID: PMC6694757 DOI: 10.3389/fmicb.2019.01811] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 07/23/2019] [Indexed: 12/20/2022] Open
Abstract
Returning straw to soil is an effective way to sustain or improve soil quality and crop yields. However, a robust understanding of the impact of straw return on the composition of the soil microbial communities under field conditions has remained elusive. In this study, we characterized the effects of wheat straw return on soil bacterial and fungal communities in a wheat–soybean rotation system over a 3-year period, using Illumina-based 16S rRNA, and internal transcribed region (ITS) amplicon sequencing. Wheat straw return significantly affected the α-diversity of the soil bacterial, but not fungal, community. It enhanced the relative abundance of the bacterial phylum Proteobacteria and the fungal phylum Zygomycota, but reduced that of the bacterial phylum Acidobacteria, and the fungal phylum Ascomycota. Notably, it enriched the relative abundance of nitrogen-cycling bacterial genera such as Bradyrhizobium and Rhizobium. Preliminary analysis of soil chemical properties indicated that straw return soils had significantly higher total nitrogen (TN) contents than no straw return soils. In addition, the relative abundance of fungal genera containing pathogens was significantly lower in straw return soils relative to control soils, such as Fusarium, Alternaria, and Myrothecium. These results suggested a selection effect from the 3-year continuous straw return treatment and the soil bacterial and fungal communities were moderately changed.
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Affiliation(s)
- Hongjun Yang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, China.,The Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Jiaxin Ma
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, China.,The Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Zhenyang Rong
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, China.,The Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Dandan Zeng
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, China.,The Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Yuanchao Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, China.,The Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Shuijin Hu
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, China.,Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, United States
| | - Wenwu Ye
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, China.,The Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Xiaobo Zheng
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, China.,The Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
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33
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Linde CC, Smith LM. Host specialisation and disparate evolution of Pyrenophora teres f. teres on barley and barley grass. BMC Evol Biol 2019; 19:139. [PMID: 31286867 PMCID: PMC6615293 DOI: 10.1186/s12862-019-1446-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 05/27/2019] [Indexed: 11/10/2022] Open
Abstract
Background Pathogens evolve in an arms race, frequently evolving virulence that defeats resistance genes in their hosts. Infection of multiple hosts may accelerate this virulence evolution. Theory predicts that host diversity affects pathogen diversity, with more diverse hosts expected to harbour more diverse pathogens that reproduce sexually. We tested this hypothesis by comparing the microsatellite (SSR) genetic diversity of the barley leaf pathogen Pyrenophora teres f. teres (Ptt) from barley (monoculture) and barley grass (outbreeding). We also aim to investigate host specificity and attempt to track virulence on two barley cultivars, Maritime and Keel. Results Genetic diversity in barley Ptt populations was higher than in populations from barley grass. Barley Ptt populations also had higher linkage disequilibrium levels, indicating less frequent sexual reproduction, consistent with the Red Queen hypothesis theory that genetically diverse hosts should select for higher levels of sexual reproduction of the pathogen. SSR analyses indicate that host-associated Ptt populations do not share genotypes and have independent evolutionary histories. Pathogenicity studies showed host specificity as host-associated Ptt isolates could not cross-infect hosts. Minimum spanning network analyses indicated two major clusters of barley Ptt. One cluster represents Maritime virulent and isolates from Western Australia (WA). Low PhiPt population differentiation between WA populations and those from Maritime and Keel, indicated a WA origin of the Maritime and Keel virulences. The main minimum spanning network cluster is represented by a panmictic population structure, represented by isolates from all over Australia. Conclusions Although barley Ptt populations are more diverse than barley grass Ptt populations, this may be a result of the size and number of founder Ptt populations to Australia, with larger and more barley Ptt populations introduced. More frequent sexual reproduction of Ptt on barley grass support the Red Queen Hypothesis and suggest evolutionary potential of pathogens on diverse hosts are high. Extensive gene flow of Ptt between regions in Australia is suggested to maintain a panmictic population structure, with human-mediated dispersal aiding in virulence evolution of Ptt on barley. Electronic supplementary material The online version of this article (10.1186/s12862-019-1446-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Celeste C Linde
- Division of Ecology and Evolution, Research School of Biology, ANU College of Science, The Australian National University, RN Robertson Building, 46 Sullivans Creek Road, Canberra, ACT, 2600, Australia.
| | - Leon M Smith
- Division of Ecology and Evolution, Research School of Biology, ANU College of Science, The Australian National University, RN Robertson Building, 46 Sullivans Creek Road, Canberra, ACT, 2600, Australia
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Hassine M, Siah A, Hellin P, Cadalen T, Halama P, Hilbert JL, Hamada W, Baraket M, Yahyaoui A, Legrève A, Duvivier M. Sexual reproduction of Zymoseptoria tritici on durum wheat in Tunisia revealed by presence of airborne inoculum, fruiting bodies and high levels of genetic diversity. Fungal Biol 2019; 123:763-772. [PMID: 31542193 DOI: 10.1016/j.funbio.2019.06.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 04/05/2019] [Accepted: 06/19/2019] [Indexed: 10/26/2022]
Abstract
Septoria tritici blotch (STB) caused by the heterothallic ascomycete Zymoseptoria tritici is currently one of the most devastating diseases of wheat worldwide. The extent of sexual reproduction of this pathogen is well documented on bread wheat, but not on durum wheat. The objective of the present study was to quantify the occurrence of Z. tritici sexual reproduction on durum wheat in the Tunisian environment. The assessment was undertaken using a triple approach combining fruiting body assessment, ascospore trapping and population genetic analyses. The results highlighted the formation of pseudothecia on leaves and stubble from the autumn until the end of the growing season. Likewise, qPCR monitoring highlighted a constant release of Z. tritici airborne inoculum during the wheat-growing season, with a peak of production at the end of the season. Genetic investigations using microsatellites revealed high levels of gene and genotypic diversities, an equal distribution of mating types, and a lack of genetic clustering within and between growing seasons. Taken together, these findings indicate that Z. tritici undergoes sexual reproduction on durum wheat in Tunisia at least to the same extent than on bread wheat in Western Europe, and that the dry and warm climate does not affect the mating process of the fungus. Frequent occurrence of sexual reproduction is a valuable knowledge to take into account in STB control strategies on durum wheat.
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Affiliation(s)
- M Hassine
- University of Carthage, National Agronomic Institute of Tunisia, LR14AGR01, Laboratory of Genetics and Cereal Breeding, National Agronomic Institute of Tunisia, Avenue Charles Nicolle 43, 1082 Tunis, Tunisia.
| | - A Siah
- ISA, INRA, Univ. Artois, Univ. Lille, Univ. Littoral Côte d'Opale, EA 7394 - ICV - Institut Charles Viollette, F-59000 Lille, France.
| | - P Hellin
- Applied Microbiology, Earth and Life Institute, Université Catholique de Louvain, Croix du Sud 2 Box L7.05.03, 1348 Louvain-la-Neuve, Belgium; Plant Protection and Ecotoxicology Unit, Walloon Agricultural Research Center, Rue du Bordia 11, 5030 Gembloux, Belgium.
| | - T Cadalen
- ISA, INRA, Univ. Artois, Univ. Lille, Univ. Littoral Côte d'Opale, EA 7394 - ICV - Institut Charles Viollette, F-59000 Lille, France.
| | - P Halama
- ISA, INRA, Univ. Artois, Univ. Lille, Univ. Littoral Côte d'Opale, EA 7394 - ICV - Institut Charles Viollette, F-59000 Lille, France.
| | - J-L Hilbert
- ISA, INRA, Univ. Artois, Univ. Lille, Univ. Littoral Côte d'Opale, EA 7394 - ICV - Institut Charles Viollette, F-59000 Lille, France.
| | - W Hamada
- University of Carthage, National Agronomic Institute of Tunisia, LR14AGR01, Laboratory of Genetics and Cereal Breeding, National Agronomic Institute of Tunisia, Avenue Charles Nicolle 43, 1082 Tunis, Tunisia.
| | - M Baraket
- National Research Institute of Rural Engineering, Water and Forestry, Rue Hédi EL Karray El Menzah IV 1004 2080 Ariana, Tunisia.
| | - A Yahyaoui
- International Maize and Wheat Improvement Center, Carretera México-Veracruz Km. 45, El Batán, 56237 Texcoco, México.
| | - A Legrève
- Applied Microbiology, Earth and Life Institute, Université Catholique de Louvain, Croix du Sud 2 Box L7.05.03, 1348 Louvain-la-Neuve, Belgium.
| | - M Duvivier
- Plant Protection and Ecotoxicology Unit, Walloon Agricultural Research Center, Rue du Bordia 11, 5030 Gembloux, Belgium.
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35
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Grandaubert J, Dutheil JY, Stukenbrock EH. The genomic determinants of adaptive evolution in a fungal pathogen. Evol Lett 2019; 3:299-312. [PMID: 31171985 PMCID: PMC6546377 DOI: 10.1002/evl3.117] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Revised: 04/02/2019] [Accepted: 04/05/2019] [Indexed: 12/16/2022] Open
Abstract
Unravelling the strength, frequency, and distribution of selective variants along the genome as well as the underlying factors shaping this distribution are fundamental goals of evolutionary biology. Antagonistic host-pathogen coevolution is thought to be a major driver of genome evolution between interacting species. While rapid evolution of pathogens has been documented in several model organisms, the genetic mechanisms of their adaptation are still poorly understood and debated, particularly the role of sexual reproduction. Here, we apply a population genomic approach to infer genome-wide patterns of selection among 13 isolates of Zymoseptoria tritici, a fungal pathogen characterized by extremely high genetic diversity, gene density, and recombination rates. We report that the genome of Z. tritici undergoes a high rate of adaptive substitutions, with 44% of nonsynonymous substitutions being adaptive on average. This fraction reaches 68% in so-called effector genes encoding determinants of pathogenicity, and the distribution of fitness effects differs in this class of genes as they undergo adaptive mutations with stronger positive fitness effects, but also more slightly deleterious mutations. Besides the globally high rate of adaptive substitutions, we report a negative relationship between pN/pS and the fine-scale recombination rate and a strong positive correlation between the rate of adaptive nonsynonymous substitutions (ωa) and recombination rate. This result suggests a pervasive role of both background selection and Hill-Robertson interference even in a species with an exceptionally high recombination rate (60 cM/Mb on average). While transposable elements (TEs) have been suggested to contribute to adaptation by creating compartments of fast-evolving genomic regions, we do not find a significant effect of TEs on the rate of adaptive mutations. Overall our study suggests that sexual recombination is a significant driver of genome evolution, even in rapidly evolving organisms subject to recurrent mutations with large positive effects.
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Affiliation(s)
- Jonathan Grandaubert
- Environmental Genomics GroupMax Planck Institute for Evolutionary BiologyAugust‐Thienemann‐Str. 224306PlönGermany
- Christian‐Albrechts University of KielAm Botanischen Garten 1–924118KielGermany
| | - Julien Y. Dutheil
- Research group Molecular Systems EvolutionMax Planck Institute for Evolutionary BiologyAugust‐Thienemann‐Str. 224306PlönGermany
- UMR 5554 Institut des Sciences de l'Evolution, CNRS, IRD, EPHEUniversité de MontpellierPlace E. Bataillon34095MontpellierFrance
| | - Eva H. Stukenbrock
- Environmental Genomics GroupMax Planck Institute for Evolutionary BiologyAugust‐Thienemann‐Str. 224306PlönGermany
- Christian‐Albrechts University of KielAm Botanischen Garten 1–924118KielGermany
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Montarry J, Bardou-Valette S, Mabon R, Jan PL, Fournet S, Grenier E, Petit EJ. Exploring the causes of small effective population sizes in cyst nematodes using artificial Globodera pallida populations. Proc Biol Sci 2019; 286:20182359. [PMID: 30963865 PMCID: PMC6367184 DOI: 10.1098/rspb.2018.2359] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 12/12/2018] [Indexed: 02/02/2023] Open
Abstract
The effective size of a population is the size of an ideal population which would undergo genetic drift at the same rate as the real population. The balance between selection and genetic drift depends on the effective population size ( Ne), rather than the real numbers of individuals in the population ( N). The objectives of the present study were to estimate Ne in the potato cyst nematode Globodera pallida and to explore the causes of a low Ne/ N ratio in cyst nematodes using artificial populations. Using a temporal analysis of 24 independent populations, the median Ne was 58 individuals (min Ne = 25 and max Ne = 228). Ne is commonly lower than N but in the case of cyst nematodes, the Ne/ N ratio was extremely low. Using artificial populations showed that this low ratio did not result from migration, selection and overlapping generations, but could be explain by the fact that G. pallida populations deviate in structure from the assumptions of the ideal population by having unequal sex ratios, high levels of inbreeding and a high variance in family sizes. The consequences of a low Ne, resulting in a strong intensity of genetic drift, could be important for their control because G. pallida populations will have a low capacity to adapt to changing environments.
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Affiliation(s)
- Josselin Montarry
- INRA, UMR1349 IGEPP, Institute of Genetic Environment and Plant Protection, 35653 Le Rheu, France
| | - Sylvie Bardou-Valette
- INRA, UMR1349 IGEPP, Institute of Genetic Environment and Plant Protection, 35653 Le Rheu, France
| | - Romain Mabon
- INRA, UMR1349 IGEPP, Institute of Genetic Environment and Plant Protection, 35653 Le Rheu, France
| | - Pierre-Loup Jan
- INRA, Agrocampus-Ouest, UMR985 ESE, Ecology and Ecosystem Health, 35042 Rennes, France
| | - Sylvain Fournet
- INRA, UMR1349 IGEPP, Institute of Genetic Environment and Plant Protection, 35653 Le Rheu, France
| | - Eric Grenier
- INRA, UMR1349 IGEPP, Institute of Genetic Environment and Plant Protection, 35653 Le Rheu, France
| | - Eric J. Petit
- INRA, Agrocampus-Ouest, UMR985 ESE, Ecology and Ecosystem Health, 35042 Rennes, France
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37
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Habig M, Kema GHJ, Holtgrewe Stukenbrock E. Meiotic drive of female-inherited supernumerary chromosomes in a pathogenic fungus. eLife 2018; 7:e40251. [PMID: 30543518 PMCID: PMC6331196 DOI: 10.7554/elife.40251] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 12/13/2018] [Indexed: 01/03/2023] Open
Abstract
Meiosis is a key cellular process of sexual reproduction that includes pairing of homologous sequences. In many species however, meiosis can also involve the segregation of supernumerary chromosomes, which can lack a homolog. How these unpaired chromosomes undergo meiosis is largely unknown. In this study we investigated chromosome segregation during meiosis in the haploid fungus Zymoseptoria tritici that possesses a large complement of supernumerary chromosomes. We used isogenic whole chromosome deletion strains to compare meiotic transmission of chromosomes when paired and unpaired. Unpaired chromosomes inherited from the male parent as well as paired supernumerary chromosomes in general showed Mendelian inheritance. In contrast, unpaired chromosomes inherited from the female parent showed non-Mendelian inheritance but were amplified and transmitted to all meiotic products. We concluded that the supernumerary chromosomes of Z. tritici show a meiotic drive and propose an additional feedback mechanism during meiosis, which initiates amplification of unpaired female-inherited chromosomes.
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Affiliation(s)
- Michael Habig
- Environmental GenomicsChristian-Albrechts University of KielKielGermany
- Max Planck Institute for Evolutionary BiologyPlönGermany
| | - Gert HJ Kema
- Wageningen Plant ResearchWageningen University and ResearchWageningenThe Netherlands
- Laboratory of PhytopathologyWageningen University and ResearchWageningenThe Netherlands
| | - Eva Holtgrewe Stukenbrock
- Environmental GenomicsChristian-Albrechts University of KielKielGermany
- Max Planck Institute for Evolutionary BiologyPlönGermany
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38
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Corcoran P, Gossmann TI, Barton HJ, Slate J, Zeng K. Determinants of the Efficacy of Natural Selection on Coding and Noncoding Variability in Two Passerine Species. Genome Biol Evol 2018; 9:2987-3007. [PMID: 29045655 PMCID: PMC5714183 DOI: 10.1093/gbe/evx213] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/16/2017] [Indexed: 02/06/2023] Open
Abstract
Population genetic theory predicts that selection should be more effective when the effective population size (Ne) is larger, and that the efficacy of selection should correlate positively with recombination rate. Here, we analyzed the genomes of ten great tits and ten zebra finches. Nucleotide diversity at 4-fold degenerate sites indicates that zebra finches have a 2.83-fold larger Ne. We obtained clear evidence that purifying selection is more effective in zebra finches. The proportion of substitutions at 0-fold degenerate sites fixed by positive selection (α) is high in both species (great tit 48%; zebra finch 64%) and is significantly higher in zebra finches. When α was estimated on GC-conservative changes (i.e., between A and T and between G and C), the estimates reduced in both species (great tit 22%; zebra finch 53%). A theoretical model presented herein suggests that failing to control for the effects of GC-biased gene conversion (gBGC) is potentially a contributor to the overestimation of α, and that this effect cannot be alleviated by first fitting a demographic model to neutral variants. We present the first estimates in birds for α in the untranslated regions, and found evidence for substantial adaptive changes. Finally, although purifying selection is stronger in high-recombination regions, we obtained mixed evidence for α increasing with recombination rate, especially after accounting for gBGC. These results highlight that it is important to consider the potential confounding effects of gBGC when quantifying selection and that our understanding of what determines the efficacy of selection is incomplete.
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Affiliation(s)
- Pádraic Corcoran
- Department of Animal and Plant Sciences, University of Sheffield, South Yorkshire, United Kingdom
| | - Toni I Gossmann
- Department of Animal and Plant Sciences, University of Sheffield, South Yorkshire, United Kingdom
| | - Henry J Barton
- Department of Animal and Plant Sciences, University of Sheffield, South Yorkshire, United Kingdom
| | | | - Jon Slate
- Department of Animal and Plant Sciences, University of Sheffield, South Yorkshire, United Kingdom
| | - Kai Zeng
- Department of Animal and Plant Sciences, University of Sheffield, South Yorkshire, United Kingdom
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39
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Bock CH, Young CA, Stevenson KL, Charlton ND. Fine-Scale Population Genetic Structure and Within-Tree Distribution of Mating Types of Venturia effusa, Cause of Pecan Scab in the United States. PHYTOPATHOLOGY 2018; 108:1326-1336. [PMID: 29771192 DOI: 10.1094/phyto-02-18-0068-r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Scab (caused by Venturia effusa) is the major disease of pecan in the southeastern United States. There is no information available on the fine-scale population genetic diversity or the occurrence of clonal types at small spatial scales that provides insight into inoculum sources and dispersal mechanisms, and potential opportunity for sexual reproduction. To investigate fine-scale genetic diversity, four trees of cultivar Wichita (populations) were sampled hierarchically: within each tree canopy, four approximately evenly spaced terminals (subpopulations) were selected and up to six leaflets (sub-subpopulations) were sampled from different compound leaves on each terminal. All lesions (n = 1 to 8) on each leaflet were sampled. The isolates were screened against a panel of 29 informative microsatellite markers and the resulting multilocus genotypes (MLG) subject to analysis. Mating type was also determined for each isolate. Of 335 isolates, there were 165 MLG (clonal fraction 49.3%). Nei's unbiased measure of genetic diversity for the clone-corrected data were moderate to high (0.507). An analysis of molecular variance demonstrated differentiation (P = 0.001) between populations on leaflets within individual terminals and between terminals within trees in the tree canopies, with 93.8% of variance explained among isolates within leaflet populations. Other analyses (minimum-spanning network, Bayesian, and discriminant analysis of principal components) all indicated little affinity of isolate for source population. Of the 335 isolates, most unique MLG were found at the stratum of the individual leaflets (n = 242), with similar total numbers of unique MLG observed at the strata of the terminal (n = 170), tree (n = 166), and orchard (n = 165). Thus, the vast majority of shared clones existed on individual leaflets on a terminal at the scale of 10s of centimeters or less, indicating a notable component of short-distance dispersal. There was significant linkage disequilibrium (P < 0.001), and an analysis of Psex showed that where there were multiple encounters of an MLG, they were most probably the result of asexual reproduction (P < 0.05) but there was no evidence that asexual reproduction was involved in single or first encounters of an MLG (P > 0.05). Overall, the MAT1-1-1 and MAT1-2-1 idiomorphs were at equilibrium (73:92) and in most populations, subpopulations, and sub-subpopulations. Both mating types were frequently observed on the same leaflet. The results provide novel information on the characteristics of populations of V. effusa at fine spatial scales, and provide insights into the dispersal of the organism within and between trees. The proximity of both mating idiomorphs on single leaflets is further evidence of opportunity for development of the sexual stage in the field.
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Affiliation(s)
- Clive H Bock
- First author: U.S. Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; second and fourth authors: Noble Research Institute, LLC, 2510 Sam Noble Parkway, Ardmore, OK 73401; and third author: Department of Plant Pathology, Coastal Plain Experiment Station, University of Georgia, Tifton 31793
| | - Carolyn A Young
- First author: U.S. Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; second and fourth authors: Noble Research Institute, LLC, 2510 Sam Noble Parkway, Ardmore, OK 73401; and third author: Department of Plant Pathology, Coastal Plain Experiment Station, University of Georgia, Tifton 31793
| | - Katherine L Stevenson
- First author: U.S. Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; second and fourth authors: Noble Research Institute, LLC, 2510 Sam Noble Parkway, Ardmore, OK 73401; and third author: Department of Plant Pathology, Coastal Plain Experiment Station, University of Georgia, Tifton 31793
| | - Nikki D Charlton
- First author: U.S. Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; second and fourth authors: Noble Research Institute, LLC, 2510 Sam Noble Parkway, Ardmore, OK 73401; and third author: Department of Plant Pathology, Coastal Plain Experiment Station, University of Georgia, Tifton 31793
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40
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Möller M, Habig M, Freitag M, Stukenbrock EH. Extraordinary Genome Instability and Widespread Chromosome Rearrangements During Vegetative Growth. Genetics 2018; 210:517-529. [PMID: 30072376 PMCID: PMC6216587 DOI: 10.1534/genetics.118.301050] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 07/18/2018] [Indexed: 12/27/2022] Open
Abstract
The haploid genome of the pathogenic fungus Zymoseptoria tritici is contained on "core" and "accessory" chromosomes. While 13 core chromosomes are found in all strains, as many as eight accessory chromosomes show presence/absence variation and rearrangements among field isolates. The factors influencing these presence/absence polymorphisms are so far unknown. We investigated chromosome stability using experimental evolution, karyotyping, and genome sequencing. We report extremely high and variable rates of accessory chromosome loss during mitotic propagation in vitro and in planta Spontaneous chromosome loss was observed in 2 to >50% of cells during 4 weeks of incubation. Similar rates of chromosome loss in the closely related Zymoseptoria ardabiliae suggest that this extreme chromosome dynamic is a conserved phenomenon in the genus. Elevating the incubation temperature greatly increases instability of accessory and even core chromosomes, causing severe rearrangements involving telomere fusion and chromosome breakage. Chromosome losses do not affect the fitness of Zymoseptoria tritici in vitro, but some lead to increased virulence, suggesting an adaptive role of this extraordinary chromosome instability.
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Affiliation(s)
- Mareike Möller
- Environmental Genomics, Christian-Albrechts University, D-24118 Kiel, Germany
- Max Planck Fellow Group Environmental Genomics, Max Planck Institute for Evolutionary Biology, D-24306 Plön, Germany
| | - Michael Habig
- Environmental Genomics, Christian-Albrechts University, D-24118 Kiel, Germany
- Max Planck Fellow Group Environmental Genomics, Max Planck Institute for Evolutionary Biology, D-24306 Plön, Germany
| | - Michael Freitag
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon 97331-7305
| | - Eva H Stukenbrock
- Environmental Genomics, Christian-Albrechts University, D-24118 Kiel, Germany
- Max Planck Fellow Group Environmental Genomics, Max Planck Institute for Evolutionary Biology, D-24306 Plön, Germany
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41
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Wu Y, Ma X, Pan Z, Kale SD, Song Y, King H, Zhang Q, Presley C, Deng X, Wei CI, Xiao S. Comparative genome analyses reveal sequence features reflecting distinct modes of host-adaptation between dicot and monocot powdery mildew. BMC Genomics 2018; 19:705. [PMID: 30253736 PMCID: PMC6156980 DOI: 10.1186/s12864-018-5069-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 09/11/2018] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Powdery mildew (PM) is one of the most important and widespread plant diseases caused by biotrophic fungi. Notably, while monocot (grass) PM fungi exhibit high-level of host-specialization, many dicot PM fungi display a broad host range. To understand such distinct modes of host-adaptation, we sequenced the genomes of four dicot PM biotypes belonging to Golovinomyces cichoracearum or Oidium neolycopersici. RESULTS We compared genomes of the four dicot PM together with those of Blumeria graminis f.sp. hordei (both DH14 and RACE1 isolates), B. graminis f.sp. tritici, and Erysiphe necator infectious on barley, wheat and grapevine, respectively. We found that despite having a similar gene number (6620-6961), the PM genomes vary from 120 to 222 Mb in size. This high-level of genome size variation is indicative of highly differential transposon activities in the PM genomes. While the total number of genes in any given PM genome is only about half of that in the genomes of closely related ascomycete fungi, most (~ 93%) of the ascomycete core genes (ACGs) can be found in the PM genomes. Yet, 186 ACGs were found absent in at least two of the eight PM genomes, of which 35 are missing in some dicot PM biotypes, but present in the three monocot PM genomes, indicating remarkable, independent and perhaps ongoing gene loss in different PM lineages. Consistent with this, we found that only 4192 (3819 singleton) genes are shared by all the eight PM genomes, the remaining genes are lineage- or biotype-specific. Strikingly, whereas the three monocot PM genomes possess up to 661 genes encoding candidate secreted effector proteins (CSEPs) with families containing up to 38 members, all the five dicot PM fungi have only 116-175 genes encoding CSEPs with limited gene amplification. CONCLUSIONS Compared to monocot (grass) PM fungi, dicot PM fungi have a much smaller effectorome. This is consistent with their contrasting modes of host-adaption: while the monocot PM fungi show a high-level of host specialization, which may reflect an advanced host-pathogen arms race, the dicot PM fungi tend to practice polyphagy, which might have lessened selective pressure for escalating an with a particular host.
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Affiliation(s)
- Ying Wu
- Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, MD 20850 USA
| | - Xianfeng Ma
- Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, MD 20850 USA
- Hunan Provincial Key Laboratory for Germplasm Innovation and Utilization of Crop, Hunan Agricultural University, Changsha, 410128 China
| | - Zhiyong Pan
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Key Laboratory of Horticultural Crop Biology and Genetic Improvement (Central Region, Ministry of Agriculture), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070 China
| | - Shiv D. Kale
- Biocomplexity Institute, Virginia Tech, Blacksburg, VA 24061 USA
| | - Yi Song
- Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, MD 20850 USA
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100083 China
| | - Harlan King
- Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, MD 20850 USA
| | - Qiong Zhang
- Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, MD 20850 USA
| | - Christian Presley
- Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, MD 20850 USA
| | - Xiuxin Deng
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Key Laboratory of Horticultural Crop Biology and Genetic Improvement (Central Region, Ministry of Agriculture), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070 China
| | - Cheng-I Wei
- College of Agriculture & Natural Resources, University of Maryland, College Park, MD 20742 USA
| | - Shunyuan Xiao
- Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, MD 20850 USA
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD 20742 USA
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42
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Ye Z, Pan Y, Zhang Y, Cui H, Jin G, McHardy AC, Fan L, Yu X. Comparative whole-genome analysis reveals artificial selection effects on Ustilago esculenta genome. DNA Res 2018; 24:635-648. [PMID: 28992048 PMCID: PMC5726479 DOI: 10.1093/dnares/dsx031] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Accepted: 07/06/2017] [Indexed: 12/31/2022] Open
Abstract
Ustilago esculenta, infects Zizania latifolia, and induced host stem swollen to be a popular vegetable called Jiaobai in China. It is the long-standing artificial selection that maximizes the occurrence of favourable Jiaobai, and thus maintaining the plant-fungi interaction and modulating the fungus evolving from plant pathogen to entophyte. In this study, whole genome of U. esculenta was sequenced and transcriptomes of the fungi and its host were analysed. The 20.2 Mb U. esculenta draft genome of 6,654 predicted genes including mating, primary metabolism, secreted proteins, shared a high similarity to related Smut fungi. But U. esculenta prefers RNA silencing not repeat-induced point in defence and has more introns per gene, indicating relatively slow evolution rate. The fungus also lacks some genes in amino acid biosynthesis pathway which were filled by up-regulated host genes and developed distinct amino acid response mechanism to balance the infection-resistance interaction. Besides, U. esculenta lost some surface sensors, important virulence factors and host range-related effectors to maintain the economic endophytic life. The elucidation of the U. esculenta genomic information as well as expression profiles can not only contribute to more comprehensive insights into the molecular mechanism underlying artificial selection but also into smut fungi-host interactions.
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Affiliation(s)
- Zihong Ye
- Department of Zhejiang Provincial Key Laboratory of Biometrology and Inspection & Quarantine, China Jiliang University, Hangzhou, China
| | - Yao Pan
- Department of Algorithmic Bioinformatics, Heinrich Heine University, Düsseldorf, Germany.,Cluster of Excellence on Plant Sciences (CEPLAS), Düsseldorf, Germany
| | - Yafen Zhang
- Department of Zhejiang Provincial Key Laboratory of Biometrology and Inspection & Quarantine, China Jiliang University, Hangzhou, China
| | - Haifeng Cui
- Department of Zhejiang Provincial Key Laboratory of Biometrology and Inspection & Quarantine, China Jiliang University, Hangzhou, China
| | - Gulei Jin
- Department of Agronomy & Zhejiang Key Laboratory of Crop Germplasm Resources, Zhejiang University, Hangzhou, China
| | - Alice C McHardy
- Department of Algorithmic Bioinformatics, Heinrich Heine University, Düsseldorf, Germany.,Cluster of Excellence on Plant Sciences (CEPLAS), Düsseldorf, Germany
| | - Longjiang Fan
- Department of Agronomy & Zhejiang Key Laboratory of Crop Germplasm Resources, Zhejiang University, Hangzhou, China
| | - Xiaoping Yu
- Department of Zhejiang Provincial Key Laboratory of Biometrology and Inspection & Quarantine, China Jiliang University, Hangzhou, China
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43
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Kobmoo N, Wichadakul D, Arnamnart N, Rodríguez De La Vega RC, Luangsa-ard JJ, Giraud T. A genome scan of diversifying selection inOphiocordycepszombie-ant fungi suggests a role for enterotoxins in co-evolution and host specificity. Mol Ecol 2018; 27:3582-3598. [DOI: 10.1111/mec.14813] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 07/13/2018] [Indexed: 12/21/2022]
Affiliation(s)
- Noppol Kobmoo
- Ecologie Systématique Evolution; Université Paris-Sud; CNRS; AgroParisTech; Université Paris-Saclay; Orsay France
- National Center for Genetic Engineering and Biotechnology (BIOTEC); National Science and Development Agency (NSTDA); Klhong Luang Thailand
| | - Duangdao Wichadakul
- Chulalongkorn University Big Data Analytics and IoT Center (CUBIC); Department of Computer Engineering; Faculty of Engineering; Chulalongkorn University; Bangkok Thailand
- Center of Excellence in Systems Biology; Faculty of Medicine; Chulalongkorn University; Bangkok Thailand
| | - Nuntanat Arnamnart
- National Center for Genetic Engineering and Biotechnology (BIOTEC); National Science and Development Agency (NSTDA); Klhong Luang Thailand
| | | | - Janet J. Luangsa-ard
- National Center for Genetic Engineering and Biotechnology (BIOTEC); National Science and Development Agency (NSTDA); Klhong Luang Thailand
| | - Tatiana Giraud
- Ecologie Systématique Evolution; Université Paris-Sud; CNRS; AgroParisTech; Université Paris-Saclay; Orsay France
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44
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Sánchez-Vallet A, Fouché S, Fudal I, Hartmann FE, Soyer JL, Tellier A, Croll D. The Genome Biology of Effector Gene Evolution in Filamentous Plant Pathogens. ANNUAL REVIEW OF PHYTOPATHOLOGY 2018; 56:21-40. [PMID: 29768136 DOI: 10.1146/annurev-phyto-080516-035303] [Citation(s) in RCA: 103] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Filamentous pathogens, including fungi and oomycetes, pose major threats to global food security. Crop pathogens cause damage by secreting effectors that manipulate the host to the pathogen's advantage. Genes encoding such effectors are among the most rapidly evolving genes in pathogen genomes. Here, we review how the major characteristics of the emergence, function, and regulation of effector genes are tightly linked to the genomic compartments where these genes are located in pathogen genomes. The presence of repetitive elements in these compartments is associated with elevated rates of point mutations and sequence rearrangements with a major impact on effector diversification. The expression of many effectors converges on an epigenetic control mediated by the presence of repetitive elements. Population genomics analyses showed that rapidly evolving pathogens show high rates of turnover at effector loci and display a mosaic in effector presence-absence polymorphism among strains. We conclude that effective pathogen containment strategies require a thorough understanding of the effector genome biology and the pathogen's potential for rapid adaptation.
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Affiliation(s)
- Andrea Sánchez-Vallet
- Plant Pathology, Institute of Integrative Biology, ETH Zürich, 8092 Zürich, Switzerland
| | - Simone Fouché
- Plant Pathology, Institute of Integrative Biology, ETH Zürich, 8092 Zürich, Switzerland
| | - Isabelle Fudal
- UMR BIOGER, INRA, AgroParisTech, Université Paris-Saclay, 78850 Thiverval-Grignon, France
| | - Fanny E Hartmann
- Ecologie Systématique Evolution, AgroParisTech, Université Paris-Sud, CNRS, Université Paris-Saclay, 91400 Orsay, France
| | - Jessica L Soyer
- UMR BIOGER, INRA, AgroParisTech, Université Paris-Saclay, 78850 Thiverval-Grignon, France
| | - Aurélien Tellier
- Section of Population Genetics, Technical University of Munich, 85354 Freising, Germany
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland;
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45
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Massonnet M, Morales-Cruz A, Minio A, Figueroa-Balderas R, Lawrence DP, Travadon R, Rolshausen PE, Baumgartner K, Cantu D. Whole-Genome Resequencing and Pan-Transcriptome Reconstruction Highlight the Impact of Genomic Structural Variation on Secondary Metabolite Gene Clusters in the Grapevine Esca Pathogen Phaeoacremonium minimum. Front Microbiol 2018; 9:1784. [PMID: 30150972 PMCID: PMC6099105 DOI: 10.3389/fmicb.2018.01784] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 07/16/2018] [Indexed: 12/30/2022] Open
Abstract
The Ascomycete fungus Phaeoacremonium minimum is one of the primary causal agents of Esca, a widespread and damaging grapevine trunk disease. Variation in virulence among Pm. minimum isolates has been reported, but the underlying genetic basis of the phenotypic variability remains unknown. The goal of this study was to characterize intraspecific genetic diversity and explore its potential impact on virulence functions associated with secondary metabolism, cellular transport, and cell wall decomposition. We generated a chromosome-scale genome assembly, using single molecule real-time sequencing, and resequenced the genomes and transcriptomes of multiple isolates to identify sequence and structural polymorphisms. Numerous insertion and deletion events were found for a total of about 1 Mbp in each isolate. Structural variation in this extremely gene dense genome frequently caused presence/absence polymorphisms of multiple adjacent genes, mostly belonging to biosynthetic clusters associated with secondary metabolism. Because of the observed intraspecific diversity in gene content due to structural variation we concluded that a transcriptome reference developed from a single isolate is insufficient to represent the virulence factor repertoire of the species. We therefore compiled a pan-transcriptome reference of Pm. minimum comprising a non-redundant set of 15,245 protein-coding sequences. Using naturally infected field samples expressing Esca symptoms, we demonstrated that mapping of meta-transcriptomics data on a multi-species reference that included the Pm. minimum pan-transcriptome allows the profiling of an expanded set of virulence factors, including variable genes associated with secondary metabolism and cellular transport.
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Affiliation(s)
- Mélanie Massonnet
- Department of Viticulture and Enology, University of California, Davis, Davis, CA, United States
| | - Abraham Morales-Cruz
- Department of Viticulture and Enology, University of California, Davis, Davis, CA, United States
| | - Andrea Minio
- Department of Viticulture and Enology, University of California, Davis, Davis, CA, United States
| | - Rosa Figueroa-Balderas
- Department of Viticulture and Enology, University of California, Davis, Davis, CA, United States
| | - Daniel P. Lawrence
- Department of Plant Pathology, University of California, Davis, Davis, CA, United States
| | - Renaud Travadon
- Department of Plant Pathology, University of California, Davis, Davis, CA, United States
| | - Philippe E. Rolshausen
- Department of Botany and Plant Sciences, University of California, Riverside, Riverside, CA, United States
| | - Kendra Baumgartner
- Crops Pathology and Genetics Research Unit, Agricultural Research Service, United States Department of Agriculture, Davis, CA, United States
| | - Dario Cantu
- Department of Viticulture and Enology, University of California, Davis, Davis, CA, United States
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46
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Wang RJ, Hahn MW. Speciation genes are more likely to have discordant gene trees. Evol Lett 2018; 2:281-296. [PMID: 30283682 PMCID: PMC6121824 DOI: 10.1002/evl3.77] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 06/15/2018] [Accepted: 07/06/2018] [Indexed: 12/27/2022] Open
Abstract
Speciation genes are responsible for reproductive isolation between species. By directly participating in the process of speciation, the genealogies of isolating loci have been thought to more faithfully represent species trees. The unique properties of speciation genes may provide valuable evolutionary insights and help determine the true history of species divergence. Here, we formally analyze whether genealogies from loci participating in Dobzhansky-Muller (DM) incompatibilities are more likely to be concordant with the species tree under incomplete lineage sorting (ILS). Individual loci differ stochastically from the true history of divergence with a predictable frequency due to ILS, and these expectations-combined with the DM model of intrinsic reproductive isolation from epistatic interactions-can be used to examine the probability of concordance at isolating loci. Contrary to existing verbal models, we find that reproductively isolating loci that follow the DM model are often more likely to have discordant gene trees. These results are dependent on the pattern of isolation observed between three species, the time between speciation events, and the time since the last speciation event. Results supporting a higher probability of discordance are found for both derived-derived and derived-ancestral DM pairs, and regardless of whether incompatibilities are allowed or prohibited from segregating in the same population. Our overall results suggest that DM loci are unlikely to be especially useful for reconstructing species relationships, even in the presence of gene flow between incipient species, and may in fact be positively misleading.
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Affiliation(s)
| | - Matthew W. Hahn
- Department of BiologyIndiana UniversityBloomingtonIndiana
- Department of Computer ScienceIndiana UniversityBloomingtonIndiana
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47
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Silva DN, Várzea V, Paulo OS, Batista D. Population genomic footprints of host adaptation, introgression and recombination in coffee leaf rust. MOLECULAR PLANT PATHOLOGY 2018; 19:1742-1753. [PMID: 29328532 PMCID: PMC6638104 DOI: 10.1111/mpp.12657] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 01/04/2018] [Accepted: 01/09/2018] [Indexed: 05/30/2023]
Abstract
Coffee leaf rust, caused by Hemileia vastatrix (Hv), represents the biggest threat to coffee production worldwide and ranks amongst the most serious fungal diseases in history. Despite a recent series of outbreaks and emergence of hypervirulent strains, the population evolutionary history and potential of this pathogen remain poorly understood. To address this issue, we used restriction site-associated DNA sequencing (RADseq) to generate ∼19 000 single nucleotide polymorphisms (SNPs) across a worldwide collection of 37 Hv samples. Contrary to the long-standing idea that Hv represents a genetically unstructured and cosmopolitan species, our results reveal the existence of a cryptic species complex with marked host tropism. Using phylogenetic and pathological data, we show that one of these lineages (C3) infects almost exclusively the most economically valuable coffee species (tetraploids that include Coffea arabica and interspecific hybrids), whereas the other lineages (C1 and C2) are severely maladapted to these hosts, but successfully infect diploid coffee species. Population dynamic analyses suggest that the C3 group may be a recent 'domesticated' lineage that emerged via host shift from diploid coffee hosts. We also found evidence of recombination occurring within this group, which could explain the high pace of pathotype emergence despite the low genetic variation. Moreover, genomic footprints of introgression between the C3 and C2 groups were discovered and raise the possibility that virulence factors may be quickly exchanged between groups with different pathogenic abilities. This work advances our understanding of the evolutionary strategies used by plant pathogens in agro-ecosystems with direct and far-reaching implications for disease control.
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Affiliation(s)
- Diogo Nuno Silva
- Departamento de Biologia Animal, Centre for Ecology, Evolution and Environmental Changes (cE3c), Computational Biology and Population Genomics Group (CoBiG)Faculdade de Ciências, Universidade de LisboaLisboaPortugal
- Centro de Investigação das Ferrugens do Cafeeiro (CIFC), Instituto Superior de AgronomiaUniversidade de LisboaOeirasPortugal
- Linking Landscape, Environment, Agriculture and Food (LEAF), Instituto Superior de AgronomiaUniversidade de LisboaLisboaPortugal
| | - Vítor Várzea
- Centro de Investigação das Ferrugens do Cafeeiro (CIFC), Instituto Superior de AgronomiaUniversidade de LisboaOeirasPortugal
- Linking Landscape, Environment, Agriculture and Food (LEAF), Instituto Superior de AgronomiaUniversidade de LisboaLisboaPortugal
| | - Octávio Salgueiro Paulo
- Departamento de Biologia Animal, Centre for Ecology, Evolution and Environmental Changes (cE3c), Computational Biology and Population Genomics Group (CoBiG)Faculdade de Ciências, Universidade de LisboaLisboaPortugal
| | - Dora Batista
- Departamento de Biologia Animal, Centre for Ecology, Evolution and Environmental Changes (cE3c), Computational Biology and Population Genomics Group (CoBiG)Faculdade de Ciências, Universidade de LisboaLisboaPortugal
- Centro de Investigação das Ferrugens do Cafeeiro (CIFC), Instituto Superior de AgronomiaUniversidade de LisboaOeirasPortugal
- Linking Landscape, Environment, Agriculture and Food (LEAF), Instituto Superior de AgronomiaUniversidade de LisboaLisboaPortugal
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48
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Wu B, Macielog AI, Hao W. Origin and Spread of Spliceosomal Introns: Insights from the Fungal Clade Zymoseptoria. Genome Biol Evol 2018; 9:2658-2667. [PMID: 29048531 PMCID: PMC5647799 DOI: 10.1093/gbe/evx211] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/29/2017] [Indexed: 12/16/2022] Open
Abstract
Spliceosomal introns are a key feature of eukaryote genome architecture and have been proposed to originate from selfish group II introns from an endosymbiotic bacterium, that is, the ancestor of mitochondria. However, the mechanisms underlying the wide spread of spliceosomal introns across eukaryotic genomes have been obscure. In this study, we characterize the dynamic evolution of spliceosomal introns in the fungal genus Zymoseptoria at different evolutionary scales, that is, within a genome, among conspecific strains within species, and between different species. Within the genome, spliceosomal introns can proliferate in unrelated genes and intergenic regions. Among conspecific strains, spliceosomal introns undergo rapid turnover (gains and losses) and frequent sequence exchange between geographically distinct strains. Furthermore, spliceosomal introns could undergo introgression between distinct species, which can further promote intron invasion and proliferation. The dynamic invasion and proliferation processes of spliceosomal introns resemble the life cycles of mobile selfish (group I/II) introns, and these intron movements, at least in part, account for the dramatic processes of intron gain and intron loss during eukaryotic evolution.
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Affiliation(s)
- Baojun Wu
- Department of Biology, Clark University, Worcester, MA, USA
| | | | - Weilong Hao
- Department of Biological Sciences, Wayne State University
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49
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Hartmann FE, McDonald BA, Croll D. Genome-wide evidence for divergent selection between populations of a major agricultural pathogen. Mol Ecol 2018; 27:2725-2741. [PMID: 29729657 PMCID: PMC6032900 DOI: 10.1111/mec.14711] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 04/05/2018] [Accepted: 04/17/2018] [Indexed: 12/30/2022]
Abstract
The genetic and environmental homogeneity in agricultural ecosystems is thought to impose strong and uniform selection pressures. However, the impact of this selection on plant pathogen genomes remains largely unknown. We aimed to identify the proportion of the genome and the specific gene functions under positive selection in populations of the fungal wheat pathogen Zymoseptoria tritici. First, we performed genome scans in four field populations that were sampled from different continents and on distinct wheat cultivars to test which genomic regions are under recent selection. Based on extended haplotype homozygosity and composite likelihood ratio tests, we identified 384 and 81 selective sweeps affecting 4% and 0.5% of the 35 Mb core genome, respectively. We found differences both in the number and the position of selective sweeps across the genome between populations. Using a XtX‐based outlier detection approach, we identified 51 extremely divergent genomic regions between the allopatric populations, suggesting that divergent selection led to locally adapted pathogen populations. We performed an outlier detection analysis between two sympatric populations infecting two different wheat cultivars to identify evidence for host‐driven selection. Selective sweep regions harboured genes that are likely to play a role in successfully establishing host infections. We also identified secondary metabolite gene clusters and an enrichment in genes encoding transporter and protein localization functions. The latter gene functions mediate responses to environmental stress, including interactions with the host. The distinct gene functions under selection indicate that both local host genotypes and abiotic factors contributed to local adaptation.
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Affiliation(s)
- Fanny E Hartmann
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland.,Ecologie Systématique Evolution, Univ. Paris-Sud, AgroParisTech, CNRS, Université Paris-Saclay, Orsay, France
| | - Bruce A McDonald
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
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50
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Schirrmann MK, Zoller S, Croll D, Stukenbrock EH, Leuchtmann A, Fior S. Genomewide signatures of selection in Epichloë reveal candidate genes for host specialization. Mol Ecol 2018; 27:3070-3086. [PMID: 29633410 DOI: 10.1111/mec.14585] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 02/21/2018] [Accepted: 02/23/2018] [Indexed: 12/31/2022]
Abstract
Host specialization is a key process in ecological divergence and speciation of plant-associated fungi. The underlying determinants of host specialization are generally poorly understood, especially in endophytes, which constitute one of the most abundant components of the plant microbiome. We addressed the genetic basis of host specialization in two sympatric subspecies of grass-endophytic fungi from the Epichloë typhina complex: subsp. typhina and clarkii. The life cycle of these fungi entails unrestricted dispersal of gametes and sexual reproduction before infection of a new host, implying that the host imposes a selective barrier on viability of the progeny. We aimed to detect genes under divergent selection between subspecies, experiencing restricted gene flow due to adaptation to different hosts. Using pooled whole-genome sequencing data, we combined FST and DXY population statistics in genome scans and detected 57 outlier genes showing strong differentiation between the two subspecies. Genomewide analyses of nucleotide diversity (π), Tajima's D and dN/dS ratios indicated that these genes have evolved under positive selection. Genes encoding secreted proteins were enriched among the genes showing evidence of positive selection, suggesting that molecular plant-fungus interactions are strong drivers of endophyte divergence. We focused on five genes encoding secreted proteins, which were further sequenced in 28 additional isolates collected across Europe to assess genetic variation in a larger sample size. Signature of positive selection in these isolates and putative identification of pathogenic function supports our findings that these genes represent strong candidates for host specialization determinants in Epichloë endophytes. Our results highlight the role of secreted proteins as key determinants of host specialization.
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Affiliation(s)
- Melanie K Schirrmann
- Institute of Integrative Biology (IBZ), ETH Zürich, Zürich, Switzerland.,Research Group Molecular Diagnostics, Genomics and Bioinformatics, Agroscope, Wädenswil, Switzerland
| | - Stefan Zoller
- Genetic Diversity Centre (GDC), ETH Zürich, Zürich, Switzerland
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Eva H Stukenbrock
- Environmental Genomics, Christian-Albrechts University of Kiel, Kiel, Germany.,Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Adrian Leuchtmann
- Institute of Integrative Biology (IBZ), ETH Zürich, Zürich, Switzerland
| | - Simone Fior
- Institute of Integrative Biology (IBZ), ETH Zürich, Zürich, Switzerland
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